all functions use rlist: avoid spare foreaches

Change memcached, admin and iproto connection to use the
buffered IO.
Make coio_writev accept a hint about the total size.
Remove fiber iov.

Now that the network layer is exception aware, slowly
transit with the rest of Tarantool subsistems to
exception-based error handling model.

Make sure fiber_create() throws an exception
if there is insufficient memory for fiber or its
stack. Make the rest of the code aware of the change.

Make all subsystems (administrative console,
replication, memcached, binary protocol) use exception-based
socket API (sio.m).

Remove all fiber members related to socket I/O.
Remove fiber->peer and fiber->cookie.
The idea of the cookie is to preserve in the WAL
the originator of the request. This information is, however,
lost when saving a snapshot. To my knowledge there is no use
of this functionality, apart from pretty-printing
the WAL.

Peer is like cookie, but is textual and is used
for logging. However, now, as long as network errors
occur outside fiber context, most of the usefulness
is lost. The only remaining case is when someone is
trying to execute a write request on a read-only port.

For all other cases, sio.m already supplies SocketError
with peer name, and this is where it's most useful.

Change a single void * pointer passed to fiber_create
to a variadic list passed to every fiber_call().

Instantiate fiber IO buffers by value.

Why this is needed: in preparation for removal of network
IO from fiber code, make sure we do less juggling
with tbufs in fiber_gc().

Remove unused code.

fiber_setcancelstate(true) in admin fiber is no longer
necessary and can lead to bugs, if admin fiber works
with wal writer queue.

If there is an exception in a background (detached) fiber,
log it to the error log.

Provide a way to modify fiber name, so that created
background fibers can be distinguished by their name
(currently they all are called "lua").

The wal writer thread could write a wrong fiber
name into the log, when logging about WAL rotation.
vsay() takes the current fiber name from a global
variable, and it's changed dynamically by the concurrent
thread (the front end thread).

Sync the WAL at close time.
Fix a race condition between wal_schedule and ev_schedule
this revealed.

A cancelled fiber could get scheduled by wal_schedule.
Do not allow to asynchronously cancel a fiber which
is a part of WAL scheduler queue.
Add a test case.

End the copyright madness. Tarantool authors maintain a shared
copyright on the code base. Remove individual copyright (c) from
specific files and put a single AUTHORS file in the project top.

A fix and a test case for Bug#911641
"box.fiber.sleep() works incorrectly if a fiber is attached".

Use symmetric scheduling for attached fibers. This allows box.insert(),
box.update(), box.delete() box.fiber.sleep() in an attached
fiber just the same way as in a detached one.

Add tests.

Now it's possible to resume() a fiber created in another fiber.

In the new Objective C 2.0 runtime, class Object was trimmed
and no longer contains + alloc, - init, - free and - subclassResponsibility,
which we use.

Implement our own base class and use it instead of the old Object.

This should fix compilation with gcc 4.7 everywhere and clang on
Darwin.

The current code can still be built with gcc 4.6.

A fix for Bug#1017905 "replication failure may leave garbage in the read
buffer".

No test case since this is a runtime error which is hard to emulate.

Clear the read buffer whenever closing a file desriptor, to remove
garbage data from the closed connection.

Tarantool/Box crashed during shutdown if a non running LUA fiber
was created.

Fiber garbage collection in Lua, initiated during shutdown,
was performed after the fiber subsystem was destroyed.

Additionally, fix a wrongly formulated assert which checks
that the fiber which is being cancelled has not been
cancelled already.

When salloc_init() fails, we call tarantool_free(),
which calls fiber_free(), which tries to destroy the fiber registry
hash, which has not been allocated.

Check that the hash has been allocated, before trying to destroy it.

This reverts commit 8dc70aac.

This patch introduces wal_mode configuration variable,
which can take either "fsync" or "fsync_delay" values.

In "fsync" mode, we open the write ahead log in O_SYNC
mode, and thus sync every write to disk.

Th fsync_delay mode is the backward-compatible mode:
in this mode, we only do fsync once every fsync_delay
seconds. If fsync_delay is 0, there is no fsync.

Otherwise, this patch is only adding auxiliary headers,
object files, etc.

Set SO_KEEPALIVE option for replication replay sockets and fiber's clients
sockets.

Update style, add comments.

lua:
box.fiber.status function was added. The function returns current fiber
status, like a cocoroutine.status() function in lua standard library.

core:
fiber_is_caller function was added. The function returns true if
checking fiber is caller of current working fiber.

An intermediate step, use size0 for 'size' temporarily,
to ensure there are no compilation errors.

This is a code review of Konstantin Shulgin's branch
refactoring-tbuf.

Add box.fiber.create(), box.fiber.resume(),
fiber.yield(), box.fiber.detach().

Add tests.

Makce fiber cancellation implementation
more robust and quick, so that it
is actually usable from Lua.
Debug.

Add fiber.cancel(), fiber.sleep(), fiber.testcancel(),
fiber.id().
Draft the fiber library interface description.

yield function was renamed to fiber_yield.