Replication relay was created (forked) after initialization
of slab allocator, and, consequently, had a very large address
space. The memory wasn't used really.

Initialize slab allocator after creation of a replication
relay process.

No test case since we don't have automation to detect that sort
of problems.

Review comments.

Conflicts:
	include/fiber.h

Remove added logging, a message with 'saving snapshot %filename'
is already printed to the log by the child. It contains
snapshot pid. Snapshot fid is not as useful once the bug
is fixed.

https://bugs.launchpad.net/tarantool/+bug/1162797

by SIGUSR1 tarantool
- didn't touch box.info.snapshot_pid
- didn't waitpid for snapshot process

Conflicts:

	include/fiber.h

(https://bugs.launchpad.net/tarantool/+bug/1160869)

flag is set.
(https://bugs.launchpad.net/tarantool/+bug/1160877)

getaddrinfo("::1") may fail if machine has no public ipv6 addresses due
to AI_ADDRCONFIG behaviour.

(https://bugs.launchpad.net/tarantool/+bug/1160869)

Lua socket object creates coio object that bind to a current
fiber, after yield it will resume it in a different fiber
context after a complete io operation.

Fix this situation by updating current coio fiber in most
lua socket operations.

https://bugs.launchpad.net/tarantool/+bug/1160789

When multiple sessions get disconnected at the same
time, the same fiber is running all disconnect triggers.
This fiber's sid was  not changed between trigger invocations,
and on_disconnect() triggrer of the next disconnected
session would see not its own session id in box.session.id(),
but the previous session's session id.

The fix is to correctly set box.session.id() before handling
any iproto request.
In on_connect() request, sid is 0, but soon it is
reset in session_create().

No test case since the bug requires that there is a full
libev queue, so that multiple on_disconnect() triggers
fire in the same loop.

libreadline already goes with libhistory compiled in,
no reason to add it to the dynamically linked library
list.
Apparently, explicitly listing libhistory leads to
the dl loader pre-loading it instead of the compiled-in
version, which, in turn, leads to a crash on the first
history search in the command line client.

The fix is to remove cmake dependency on libhistory
as well as on libncurses, which we don't need either
(always require libtermcap).

A session trigger would always use the same coroutine, for both connect and
disconnect, as well as for multiple sessions.

If a trigger runs insert() or update(), anything that yields the current
coro, the coro stack would get corrupted for the next parallel invocation.

Use an own coroutine for each invocation of a session trigger.

Tarantool showed random error (in tarantool.log) if client
disconnected: SocketError used filehandle instead errno.

Conflicts:
	third_party/README

Preserve the zero-warnings patch.

fiber.name and fiber->gc_pool.name are always the same thing.
Don't store the name twice.