Implement a basic SQL parser.

Implement SQL statements: INSERT, UPDATE, DELETE,
PING.

Add a test case that tests INSERT/SELECT/DELETE.

Other changes:

Remove support for result-prefix from admin.py
Rename admin.py to tarantool (tarantool client).
Add readline support to tarantool client.
Make sql.g and sql.py independent from yapps
Add gdb support to ./test-run
Disable all optimizations when compiling with DEBUG.
Fix a few bugs discovered by trial and error in silverbox
protocol description.
Add automatic reconnection in case of server disconnect
to test connections. This is used to automatically
reconnect to the server after server restart or reinstall.
Implement soft and hard (with and without removal of vardir)
server restart.
Make show.test results independent from other tests (data I/O
skews statistics, and there is no way to reset it without
restarting the server).
Add  TCP_NODELAY to fiber sockets.