It's useless - it only checks that certain counters are present, but
doesn't give a damn about what they show. At the same time, I have to
update its output every time I modify vinyl statistics, which I'm doing
pretty often these days. So let's ditch it - I'll rewrite it from
scratch after I'm done reworking vinyl statistics.

gh-2520: add comments explaining the test case for gh-2520 (upsert
caching).

Use a tuple cache to turn an UPSERT in the PREPARE, if the cache
contains a tuple with the exact same key. The UPSERT can be applied
to the cached tuples, because
1. The cache always contains only REPLACE statements;
2. The cache always contains only newest statements.

Closes #2520

When an UPSERT is prepared, it can use a cached statement to be
turned into REPLACE. But now it doesn't use the cache.

Test for #2520

Minor style fixes to improve code readability. In scope of gh-2529.

Do not unlock endpoint until a flushing async message is sent and do not
destroy endpoint until last pipe release endpoint lock. Fixed #2529

* use name_len and sz consistently across all patches working with names
  and lengths
* do not delete user_def for a system user during init
* use calloc(), since we're using it for index_def as well.

Need for #944

In scope of gh-2547 (lost of space access control lists during truncate).

* use an existing index_def from the new space instead.

IMO makes the code a bit easier to follow.

In scope of work on gh-944 (variable length object names).

* we use name_len for name length in most of the places,
  len is a widespread abbreviation for length

* add comments

Needed for #944

Malformed MessagePack can cause `int k` counter overflow
inside mp_check()/mp_next().

See https://github.com/tarantool/nginx_upstream_module/issues/79
See https://github.com/rtsisyk/msgpuck/issues/16
Closes #2540

In case of default log output
flag o_NONBLOCK is not set to descriptor

Follow up 15a9af26

exp2(64) <= UINT64_MAX is true due to type conversion.
Use exp2(64) instead of UINT64_MAX (optimized out even on -O0).

Fixes buggy box/indices_any_type.test.lua on x86_64

Closes #2472

ffi.new('long', x) and ffi.new('unsigned long', x) uses arbitratry
user-defined ctypeid instead of built-in CTID_INT32 and CTID_UINT32.
Our tonumber64() implementation is not ready for that. Remove these
two test cases and move forward. Nobody cares.

Fixes box/misc.test.lua on i386 and armhf

Follow up #2459

lua_tointeger() is equivalent to (ptrdiff_t)lua_tonumber(L),
which causes precision loss on 32-bit systems when you expect
to get a proper uint32_t value. LuaJIT stores numbers as doubles,
so lua_tointeger() makes absolutely no sense.

Replace lua_tointeger() with lua_tonumber() everywhere except
cases when result is converted to int or lua_Integer.

Fixes box/indices_any_type.test.lua on i386 and armhf

Closes #2459

It is unsafe, because system spaces use triggers to keep records in sync
with internal objects while space truncation doesn't invoke triggers.

Closes #2523

Currently, space.create must insert an entry into 'truncate' system
space - if it does not, space.truncate won't work. This is incontinent,
as it makes it impossible to create spaces by simply inserting a tuple
into the 'space' system space via iproto API. So let's insert entries
into truncate space lazily, on the first space truncation.

Closes #2524

Space truncation is implemented as recreation of a space and all its
indexes. On success the original space is deleted by the commit trigger,
while on failure the new space is deleted by the rollback trigger. The
commit/rollback triggers are always called before commit/rollback engine
methods, which makes space truncation incompatible with transactions:
engine commit/rollback may access a space that have already been deleted
by commit/rollback trigger installed by space truncation, resulting in a
crash. So let's forbid to use space.truncate from a transaction until
triggers are made transaction-friendly.

Closes #2525

Closes #2531

Part of #2507

In order of xrow library creating, exceptions must be removed
from xrow.cc, before renaming xrow.cc to xrow.c.

Part of #2507

* Fix handling of encoded data
* Remove \n added by libyaml
* Add a test case

Follow up #128

CURLOPT_POST option without explicitly set CURLOPT_POSTFIELDS caused
libcurl to use some internal implementation of CURLOPT_READFUNCTION,
which reads body from stdin by default.

Provided test case only covers argument handling because there is no
repetable way to check reads from stdin from our test suite.

Closes #2530

Old variant converted tuple to Lua table and then encoded to yaml
New variant encodes tuple to yaml directly.

Results of benchmarking with:

	old: 1m27.555s
	new: 0m48.738s
	Acceleration 44%

Closes #128

No semantic changes.

Needed for #128

This code was added by me, it is not covered by lua-yaml
copyrights and can be moved to src/.

See cd0d6f25 "incorrect error handling in lyaml".

Needed for #128

* Inline IS_PRINTABLE macros into check_utf8()
* Rename yaml_check_utf8() to utf8_check()
* Get rid of libyaml-private dependency for lua-yaml

Needed for #128

In our terminology, page index is index of pages in a run while row
index is index of rows in a page. Rename page index to row index where
appropriate.

Tarantool should not crash if one space was truncated simultaneosly from
two fibers.

Closes #928

Follow up f1862699 ("vinyl: test vylog error handling")

Forgot to update it after adding a new errinj code - my fault :-(