Marshall replication using the primary port.

Split iproto requests into two categories: DML and admin.  Change
PING request code to 64, to lay within admin request range.
Perform administrative requests synchronously, without pushing
them into an event queue.
Add a new administrative request, IPROTO_SUBSCRIBE.

Use dynamic memory for struct iproto_request. Introduce memory
management.

Remove replication_port from the configuration file and
update tests.

Fix the test runner so that it correctly generates
replication_source to point to the primary port.
Add variable arguments to IllegalParams.
Move replia-related recovery methods to a new header, replica.h.

Remove a debug printout from box.net.lua

Update tests.

Allow start of tarnatool_box in #! form.

Remove script_dir.

Make all configuration options optional (primary_port
was the last one required).
Make the configuration file itself optional.

If no watcher is started for the event loop, either based on
the config file settings, or in the #! script, do not start the event loop.

Update the test runner to take the new changes into account.

Fix a bug in symbols_load() when no symbols
could be loaded when path to executable was neither
relative nor absolute (but based on PATH).

Fix a bug with ignored return value of slab_arena_create()
in tuple.cc

Rationale:
Any error which implies a system administrator action needs to be
marked explicitly in the log, so that it's easy to find and act
upon.

This change the number of log levels, so the default log level was
bumped from 4 to 5. Installations which set the log level
explicitly need to adjust their setting.

This file was mistakenly removed by 80d358bd

Review fixes:

- New configuration variable 'replication_protocol'
is defined in the configuration file. The original patch
would hand-craft it into generated files.
- Simplified  numeric version id generation.
- Removed timeouts from new sio_* calls. They did't quite work,
especially with blocking sockits. Timeouts should at least use
select(), which updates wait time on exit..
- Removed include cfg/tarantool_box_cfg.h into recovery.cc, instead
passed around all arguments explicitly.
- Removed unused headers.
- reused handshake code in master and replica
- simplified handshake in replica fiber
- removed clutter
- touched here and there.

Provide open_memstream() implementation for system which
miss it (Mac OS X).

Remove memcached support in 1.6.
We're about to change the type system.
About to add authentication.
This all makes supporting memcache within the core too cumbersome.

Fix confetti error output. Remove redundant cfg_reload(). Make sure we
produce a Lua error on error.
Remove duplicate code.
Style renames.

Store the information about spaces in a pre-recreated
system space.

https://blueprints.launchpad.net/tarantool/+spec/space-ddl

Remove space configuration from confetti.
Use transaction and space triggers to run post-DML
actions to perform DDL changes.

Implement a Lua FFI binding to disable tests.

Temporarily disable space-loading code in tarancheck
and tarantar (this breaks them).

Mostly all tests are broken.
Memcached is disabled (non-functional).

Incompatible change,
https://blueprints.launchpad.net/tarantool/+spec/cardinality-arity

cardinality is how many unique elements a set contains. wrong term
for the max number of fields in a tuple

Implement blueprint
https://blueprints.launchpad.net/tarantool/+spec/wal-mode-none

Add wal_mode = none setting.
It's possible to chagne wal_mode without restart.

When wal_mode = none, we don't write to WAL.
It's still possible to take a snapshot.

Replication and hot standby are currently not
operational in this mode.

Do not use bundled libobjc on Darwin.
Refactor cmake scritps: introduce os.cmake, arch.cmake,
compiler.cmake, libobjc.cmake, luajit.cmake.

Remove the hack with building libobjc/luajit as a
dependency on cfg.

Do not specify -ggdb when compiling with clang.

Add -fno-objc-legacy-dispatch and -fobjc-nonfragile-abi
when compiling with CLang on Linux.

Remove -fgnu-runtime when compiling with gcc on Mac.

Many minor cleanups.

Add a makefile to libobjc.

script_dir option defines path to a directory which contains the init.lua file.

Make snap_io_rate_limit and io_collect_interval dynamic.
Add a test case.
Update the user guide.

Update the manual and the configuration file
to reflect the new WAL writer architecture.

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.