Lua: add CALL command to the binary protocol.

CALL accepts flags and a tuple (list of fields).

Add CALL support to the sql.g parser (Python
testing environment).

Add two new error codes: ER_PROC_LUA (an
error inside Lua procedure) and ER_NO_SUCH_PROC.

Since so far there is no way to create a stored
procedure (one needs to rebuild Tarantool to pre-load it),
this addition has little practical use.