Some pragmas turn out to be useless and can't be applied to Tarantool's SQL.
Moreover, couple of them lead to assertion faults.
List or removed pragmas:
- synchronous
- empty_result_callbacks
- WAL_autocheckpoint
- WAL_checkpoint
- secure_delete
- database_list
- data_version
- compile_options
- application_id
- user_version
- pragmas connected with HAS_CODEC macro
- pragmas connected with heap memory managment

This change removes REINDEX from keywords and also disables tests
which were using this syntax.

This patch affects only parser, REINDEX implementation still exists,
because it is planned to be fixed and enabled in the scope of #3195.

Note that REINDEX keyword is still in '%fallback' directive in
'parse.y'. Reserved keywords included there to avoid situation when
a keyword has no usages within 'parse.y' file.

Fixes #2174

Fix non-working 'INDEXED BY' clause for SELECT statement,
which caused syntax-error during execution.

Closes #2996

Type of an operation for struct request can be passed directly
with no "proxying" by special codes.

1) Code is completely unreadable and complicated by strange
   optimizations;
2) It still supposes, that there can be multiple statements in a
   single string;
3) It pushes first letter of affinity together with column names
   - why? It is not used anywhere.

Lets remove prepared statements list, affinity first letters
pushing.

Remove unused error codes, use enum instead of
defines. Later the prefix SQLITE_ must be removed -
see #3315.

And rework sqlite3CompleteInsertion. Before the patch it
* accepts actually unused pTab;
* array of records to insert in different indexes, but inserts
  only one;
* has sqlite code style.

Code style fix is obvious. PTab is used only to check, that it is
not a view and to check, that a first index is primary:
1) caller functions already guarantee the pTab is not a view;
2) regardless of a first index nature: primary or not - it is not
   used here. It is useless check. With the same success we can
   check this in each function, that uses struct Table.

Array of records to insert makes no sense, since insertion is
being done in a primary index only. It is enough to pass a
register with a primary index tuple.

Filed gh-3311 to remove this export soon.

Fixes #3310.

If the size of a transaction is greater than the configured memory
limit (box.cfg.vinyl_memory), the transaction will hang on commit
for 60 seconds (box.cfg.vinyl_timeout) and then fail with the
following error message:

  Timed out waiting for Vinyl memory quota

This is confusing. Let's fail such transactions immediately with
OutOfMemory error.

Closes #3291

Extract expressions parsing into separate routine to
allow Tarantool's backend compile DEFAULT statements w/o
SQL machinery at all. So far, for DEFAULT values no context
is needed: only constant expressions and built-ins are allowed.
In future, table context will be added to allow use column
values for CHECK constraint expressions.

Move DEFAULT string value to space_def. Move compiled expresion
to field_def as well. Reason not to move compiled expression
to tuple_field as follows: we do not want to engage parser
during tuple validation. So, do it in alter.cc.

In order to allow expression duplication in alter.cc: expose
those routines from expr.c and make their names correspond to
coding style.

Since recovery is performed before SQL fronend initialization:
split it into two pieces: 1. create SQL handler, enable
all subsystems 2. Do recovery.  This will allow to run
parser during recovery, since it needs db handle so far.

Part of #3235

Remove functions to find DB by name. Not used anymore,
was used by SQL legacy code.

_schema represented as key-value storage for various
values common for Tarantool, like next id for space creation.
SQL requires format to be fully specified for columns being
access. Unfortunatelly, _schema is inserted into _space
before _space's format is set and since DD triggers are
disabled during upgrade, format for _schema tuple in _space
stays the same. So, set value nullable field in upgrade,
regenerate initial snap, update tests.
Also, as far as _schema's tuple in _space is not updated:
relax fieldno check in sql.c

In case of sudden power-loss, if data was not written to WAL but
already sent to remote replica, local can't recover properly and
we have different datasets. Fix it by using remote replica's data
and LSN comparison.

Based on @GeorgyKirichenko proposal and @locker race free check.

Closes #3210

Stay in orphan (read-only) mode until local vclock is lower than
master's to make sure that datasets are the same across replicaset.
Update replication/catch test to reflect the change.

Suggested by @kostja

Needed for #3210

IPROTO_OPTIONS can be used in the future for request types,
different from IPROTO_EXECUTE.

IPROTO_SQL_ROW_COUNT is not a top level key in an iproto response
and can be moved into a separate enum.

Closes #3148

Text console tried to learn about SIGPIPE before its raising
by read-before-write. If a socket is readable, but read returns
0, then it is closed, and writing to it can raise SIGPIPE. But
Tarantool ignores SIGPIPE, so the process will not be terminated,
write() just returns -1.

The original code checks for SIGPIPE, because when Tarantool is
run under debugger (gdb or lldb), the debugger by default sets
its own signal handlers, and SIGPIPE terminates the process.

But debugger settings can be changed to ignore SIGPIPE too, so
lets remove this overengineering from the console code.

If a remote host is unreachable on the first connection attempt,
and reconnect_after is set, then netbox state machine enters
error state, but it must enter error_reconnect. Do it.

The bug was introduced by me in
d2468dac.

EV_USE_REALTIME and EV_USE_MONOTONIC, which force libev to use
clock_gettime, are enabled automatically on Linux, but not on OS X. We
used to forcefully enable them for performance reasons, but this broke
compilation on certain OS X versions and so was disabled by commit
d36ba279 ("Fix gh-1777: clock_gettime detected but unavailable in
macos"). Today we need these features enabled not just because of
performance, but also to avoid crashes when time changes on the host -
see issue #2527 and commit a6c87bf9 ("Use ev_monotonic_now/time
instead of ev_now/time for timeouts"). Fortunately, we have this cmake
defined macro HAVE_CLOCKGETTIME_DECL, which is set if clock_gettime is
available. Let's enable EV_USE_REALTIME and EV_USE_MONOTONIC if this
macro is defined.

Closes #3299

When a vylog transaction is rolled back, we always reset vy_log.tx_size.
Generally speaking, this is incorrect as rollback doesn't necessarily
remove all pending records from the tx buffer - there still may be
records committed with vy_log_tx_try_commit() that were left in the
buffer due to write errors.  We don't rollback such records, but we
still reset tx_size, which leads to a discrepancy between vy_log.tx_size
and the actual length of vy_log.tx list, which further on results in an
assertion failure:

  src/box/vy_log.c:698: vy_log_flush: Assertion `i < vy_log.tx_size' failed.

We need vy_log.tx_size to allocate xrow_header array of a proper size so
that we can flush pending vylog records to disk. This isn't a hot path
there, because vylog operations are rare. Besides, we iterate over all
records anyway to fill the xrow_header array. That said, let's remove
vy_log.tx_size altogether and instead calculate the vy_log.tx list
length right in place.

Currently, we use mh_foreach, but each object is on an rlist, which
suits better for iteration.

The new method is called if index creation failed, either due to WAL
write error or build error. It will be used by Vinyl to purge prepared
LSM tree from vylog.

Introduce limitations on combinations of box.cfg parameters.
* Add restriction on log type file and log_nonblock=true.
* Add restriction on log type syslog and log_format json.
* Each restriction creates error in case of its violation.
* Change log_nonblock default value to nil, which means default values
of log_nonblock corresponding to type of logger.
* Add box_getb function for receiving bool parameters from cfg.

Relates #3014 #3072

The bug was that logging we passed to function write
number of bytes which may be more than size of buffer.
This may happen because formatting log string we use vsnprintf which
returns number of bytes would be written to buffer, not the actual
number.

Fix this with limiting number of bytes passing to write function.

Close #3248

To facilitate performance analysis, let's report not only 99th
percentile, but also 50th, 75th, 90th, and 95th. Also, let's add
microsecond-granular buckets to the latency histogram.

Closes #3207