Assign is_nullable property for each column in order to fix all sql
tests after reverting MP_NIL comparators in previous commit.

Closes #3009

This reverts commit a2f574e3.

After TableLock opcode removal, need to re-generate
opcode definitions file.

Removed OP_ParseSchema, OP_TableLock.
All other dead code connected to locking of open tables (for both
reading and writing) removed as well.
Remove auth.c file, it is not used anymore.

Few opcodes like OpenRead/OpenWrite exepcted 3rd argument to be DB
descriptor. Now there's a single DB backend and there's no need
for any descriptors. Remove from VDBE, fix code generator, update
opcode descriptions.

Closes #2855

  Make collation tokens obey ANSI ISO standard rules for identifiers.

Related to #2818

Closes #2653, #2121

  Thsis patch do two main changes:
  1. Delete SQLite's coll structure & replace it with Tarantool's
  2. Delere SQLite's create coll mechanism

  Tarantool can not easily support create collation mechanism of SQLite,
because collations must:
  - be persistent
  - be the same in tuple comparator and SQL Mem comparator
  Although new collations are limited, suggested ICU collations cover the
main set of use-cases. ICU supports:
  - Different locales & different strengths & other options...
  - Nimeruc stringths comparation.

  That is why we limit collation api at this point.

Part of #2121

  collation_list pragma should change as the way collations work changes.
To enumerate all collations one have to iterate space for now.

  This feature is required by SQL, because searching collations by name is
common operation there.

  Is implemented by creating extra hash table.

This is the second attempt to remove encodings.
At this point Tarantool SQL supports only UTF-8 encoding.

Part of #2295

Part of #2121

Deletion of rows from table (which is part of DROP TABLE procedure) is
wrapped in transaction now. If any Foreign Key violations occur, then
rollback transaction and halt execution of statement. Otherwise, commit
changes and continue DROP TABLE routine. This logic is implemented by
OP_FkCheckCommit opcode.
Added tests for this case.

Closes #2953

  There were analogies of those functions in Tarantool. This commit makes
SQL reuse them.
  All crutches (undef) are deleted.

Added new opcode OP_RenameTable, which implements
SQL statment: ALTER TABLE old_name RENAME TO new_name;
The main idea is to replace corresponding tuple in _space.
New tuple will contain new name and new SQL statement, which
creates this table. If it is parent table for foreign key,
update SQL statement of child table. Then, remove old name
from hash table and by calling callback function from VDBE,
update database schema with new table name. After all,
in the same way update triggers' statements in _trigger table,
if any exist.

Closes #2204

Closes #2506

Opcode OP_FCopy copies integer value of register P1 into
register P2. However, if third operand contains flag
OPFLAG_NOOP_IF_NULL and reg[P1] == NULL, then it does nothing.
It could lead to wrong behaviour, when reg[P2] is undefined:
in some cases VDBE uses reg[P2] instantly after OP_FCopy.
So, if reg[P2] is undefined, simply assign it to MEM_Null.

Closes #2949

Most tests are converted from original SQLite test suite.
Tests for DEFERRED constraint are not included since it is
currently broken and there is no opportunity to test it.

Applier must not update the replication lag upon receiving a packet
containing an error, because those packets don't have timestamps.

Closes #2965

Remove `message` field from blacklist, because JSON and plain
loggers are mutually exclusive.

Fixes #2923

    For some reason 'tnum' attribute for pk was set in convertToWithoutRowid
function, while for other indexes it was set in sqlite3CreateIndex. The if
clause in sqlite3CreateIndex was filtering not only PK, but inline unique
indexes too.

    Now 'tnum' is always set in sqlite3CreateIndex procedure.

Closes #2808

* Add pbkdf2 hashing API
* Wrapper of OpenSSL

Closes #2874

vy_read_iterator_restore_mem() is called after a yield caused by a disk
read to restore the position of the iterator over the active in-memory
tree. It assumes that if a statement inserted into the active in-memory
tree during the yield is equal to the statement at which the read
iterator is positioned now (curr_stmt) by key but is older in terms of
LSN, then the iterator must be positioned at a txw statement. However,
the iterator could be positioned at an uncommitted statement stored in
the cache before the yield. We don't restore the cache iterator after a
yield, so if the new statement has been committed, its LSN will be less
than the LSN of the uncommitted statement stored in the cache although
it is indeed newer. This results in an assertion failure:

  vy_read_iterator.c:421: vy_read_iterator_restore_mem: Assertion `itr->curr_src == itr->txw_src' failed.

To fix this, let's modify the code checking if the iterator should be
repositioned to the active in-memory tree (mem_src) after a yield:
instead of comparing statement LSNs, let's reposition the iterator
unless it is currently positioned at a txw statement as it is the only
case when curr_stmt can be newer than the newly inserted statement.

Closes #2926

  It is not very important change, but implementing collations in SQL required
to either delete const modificator from some functions in SQL or make
coll_cmp_f arguments to be const. The second option were chosen because it
makes more sense.

  This renaming is important, because searching collations by name is needed
for 1.8 branch. In 1.8 there are two functions for searching collation:
  - coll_cache_id
  - coll_cache_name

  Renaming is also important because new format is closer to similar functions
in other modules.

In order to use fio in conjunction with ibuf, we need to extend read(),
pread(), write(), pwrite() so that they can take a C buffer instead of
a Lua string. The syntax is as follows:

  read(size) -> str
  read(buf, size) -> len

  pread(size, offset) -> str
  pread(buf, size, offset) -> len

  write(str)
  write(buf, size)

  pwrite(str, offset)
  pwrite(buf, size, offset)

See #2755

Deleted all system code connected with Windows and esoteric OS,
including vxworks, dragonfly etc. Now only UNIX systems are supported.

Closes #2876

Closes #2934

On disconnect applier input buffer can contain some unparsed data, clear
this.

Fixes #2932

Implement ':isfunction()' test function  in Tap testing framework
that checks whether type of an argument is 'function'.

Closes #1859

Since commit 7d67ec8a ("box: generate LSNs for rows received during
initial join"), we assign fake, monotonically growing LSNs to all
records received during initial join, because Vinyl requires all indexes
to have a unique LSN for identification in vylog. The problem is there's
a number of records (about 60) that have LSN 0 on the master - these are
bootstrap records. So if there are N such records, the index that has
LSN X on the master will have LSN (N + X) on the replica if sent during
initial join. But there may be another index with the same LSN on the
master (i.e. N + X). If this index is sent on final join or subscribe
stage, the replica will fail to make a checkpoint or recover, spitting
an error message similar to the one below:

  coio vy_log.c:2002 E> failed to process vylog record: create_index{index_lsn=68, space_id=12345, key_def=[0, 'unsigned'], }
  main/101/replica vy_log.c:1446 E> ER_INVALID_VYLOG_FILE: Invalid VYLOG file: Duplicate index id 68
  main/101/replica vy_log.c:2117 E> failed to load `./00000000000000000000.vylog'
  main/101/replica F> failed to create a checkpoint

Presently, the problem is 100% reproducible by

  test_run.py --conf vinyl engine/replica_join

To fix it, let's revert the aforementioned commit and instead assign
fake LSNs only to vinyl records, not to all records received during
initial join - after all it's vinyl that needs this, not memtx.

Actually, we already use the same technique for DML records in vinyl -
see vy_join_ctx::lsn - except there we assign fake LSNs on the master's
side. This was done for historical reasons - we could as well assign
them on the replica, but that would require some refactoring done later.
So let's use the same fake LSN counter for both cases.

 - Log debug messages at VERBOSE log level. Currently, the only way to
   debug a vylog failure in production is enabling DEBUG log level, but
   that basically floods the log with tons of not so important messages.
   There are not that many vylog messages so it should be OK to log them
   with say_verbose().

 - Report the filename on failure to load or save a vylog in order to
   simplify identification of the corrupted file.

 - Log some critical errors, such as error processing a vylog record or
   failure to flush the vylog for recovery.

 - Add sentinel messages for log rotation, saving, and loading, logged
   at VERBOSE level. This will help matching dumped log records to high
   level operations that emitted them.

 - Remove debug logging from the vy_recovery callback, which is invoked
   by vy_recovery_iterate() and vy_recovery_load_index(), as it is a
   responsibility of the caller to write log messages there, not of
   the vylog internal implementation. Besides, dumping all replayed
   records there is not really necessary as they are dumped while vylog
   is loaded anyway (see vy_recovery_new()), which should be enough for
   debugging.

During recovery we apply rows that were successfully applied either
locally before restart or on the master so conflicts are impossible.
We already skip the uniqueness check for primary indexes in this case.
Let's skip it for secondary indexes as well.

Closes #2099

The write iterator never discards DELETE statements referenced by a read
view unless it is major compaction. However, a DELETE is useless in case
it is preceded by another DELETE for the same key. Let's skip such
tautological DELETEs. It is not only a useful optimization on its own -
it will also help us annihilate INSERT+DELETE pairs on compaction.

Needed for #2875

This file used to be smaller so not having extra forward
declarations seemed to be reasonable. Now it's time to split the
code of iproto_msg and iproto_connection. No semantical changes.