This saves one malloc() per channel and tells the GC more
about how much memory is taken by a channel.

tarantoolctl: Don't assume sophia_dir is a subdir of vardir,
create everything on the top level.

tarantoolctl: marginally fix reload, but see gh-824

fio: fix numerous bugs with failure of lua_tostring(), add tests.

A minor style fix, update result file.

* INDEX_EXTENT_SIZE changed back to 16kB

Add tests.

Don't register second-level modules (e.g. box.info) in package.loaded

Conflicts:
	src/lua/bsdsocket.lua
	test/box/bsdsocket.result

Also fix :send() and :write()

* Minor fixes of matras

Conflicts:
	src/lua/digest.lua
	test/box/digest.result
	test/box/digest.test

Add a functional test for statement-level rollback.

Check that rollback actually frees the rolled back data in wal_off/oom.test.
Also check that slabs are reused and returned to the pool when they
have no tuples.

Prerequisite for #817. Other changes:

 - Add IteratorGuard structure to call iterator_close().

* implement two new calls:
  box.error.last() - returns last error, if any, as a Lua table
  box.error.clear() - clears the last error

* add an alias for box.error(), box.error.raise()

 - mysql moved to https://github.com/tarantool/mysql
 - pg moved to https://github.com/tarantool/pg

Please consult documentation on GitHub for more details.

Encapsulate trigger management, as well as undo managemnt
specific to memtx in the engine. Fix a potential memory leak
in MemtxEngine::rollbackStatement(), with wrong reference counting
for rolled back tuple.

Always generate redo record, even in wal_off=true mode, this
simplifies txn_commit().

*) fixed several comments and minor bugs
*) after CR fixes

Update comments, rename matras_extents_count() to matras_extent_count().