Partially reverts squashed 316d4e3a

iproto thread can add quirks to thread scheduling, replace
single-call yields with yields in a loop.

Correct return value of ipc_channel_put(), since
it may return an error if the channel is closed.

Make get/put functions inline.

Remove a public declaration for ipc_channel_is_readonly() (towards
removing the concept of readonly altogether).

This test was disabled by me during 1.6 async-master-master development.
Since Tarantool doesn't use proc_title for replication status anymore,
I added a new test that check box.info.replication.

Linux-specific option obsolete since kernel 2.2

Wait() no longer called hence waiters not initialized. Does it make
sence to have a test for :waiters (undocumented internals)?

- Waiting on a brand new socket (neither listen nor connect called)
  completes immediately with HUP status on Linux. However on FreeBSD/osx
  it never completes.

- Attempting to connect to a port bound on a loopback interface which is
  not yet listening yield ECONNREFUSED in blocking mode on Linux. On
  FreeBSD/osx blocking connect never completes ("never" means it doesn't
  complete in a reasonable time).

- Calling shutdown() on a listening socket works in Linux but in
  FreeBSD/osx it doesn't.

iproto thread can add quirks to thread scheduling, replace
single-call yields with yields in a loop.

I've added default tuple fields check against primary index key.
Primary key can yet be updated, but an old key will be
silently used anyway (copy used from update object).

Added tests.

ps. maybe it is better to validate upsert ops on execute?

Work the same way as box.stat does.

Support access by index: box.sophia['compaction.page_size']
and by call box.sophia()

gh-1017 double-run bug fixed, and fixed same bug in stat_net. But bug with probability doesn't repeated

gh-1017 double-run bug fixed, and fixed same bug in stat_net. But bug with probability doesn't repeated

Make code in alter.cc less error prone and less verbose.
Miscellaneous cleanups.

Fixed a pair of minor bugs:
1)Fixed multidim_test, it could occasionally crash
2)Fixed rtree_misc.test.lua, snapshot test part
3)Reverted another rtree key mode -
  ind:select{0, 0, 10, 10} and
  ind:select{{0, 0, 10, 10}} - both works now

* make sure long-run tests pass
* more systematic approach to downcasts to MemtxIndex in
alter/system spaces code

Support multi-part keys. Allow key duplicate
compaction. Reduce storage cost, encode metadata,
do not store msgpack (except value part).
Reconstruct tuple on read using index schema.

[replication]

JOIN support temporary put to not working
condition: there is no way to access possibly
deleted space schema during the operation
for a tuple reconstruction
(multi-thread).

recreate space key_def during join; enable join

sophia: make every operation asynchronous

sophia: fix join cursor and tests

sophia: implement delayed update operation

sophia: make delete write-only

implement Handler::executeReplace

sophia: merge fixes

make upsert operation an engine specific

sophia: make update logic common to memtx

sophia-integration: switch to Sophia v1.2.3; implement upsert

sophia: add half_commit mode support

This mode disables conflict resolution for
'prepared' transactions and solves the issue with
concurrent write-write conflicts during wal write/yield.

sophia: do not allocate tuple during replace or update; refactoring

sophia: extend and reorganize test suite

sophia: implement box.sophia()

sophia: #681: support or produce error on space::alter

sophia: extend recover tests

sophia: add separate iterator tests

box: enable per-engine select

    * add executeSelect() into engine handler API
    * add MemtxIndex; move preallocated m_position from Index to MemtxIndex
    * remove it->close()
    * remove IteratorGuard class

    note: Sysview and Sophia engines yet share the same select code in
    engine::executeSelect() (which does iterator alloc-free)

box: remove close call from box_iterator_free()

Reason: net.box depends on src/box/lua/tuple.h, src/box/lua/schema.lua,
src/box/lua/call.cc and these dependencies impossible to fix.

box.cfg{} is not required for net.box.