Partial fix to #463, http://bugs.skysql.com/show_bug.cgi?id=463

log_manager.cc: fixed block buffer overflow. Queries are logged to trace log and long queries exceed the bufsize in length. Those were written beyond allocated memory areas.
mysql_client_server_protocol.h: added mysql_protocol_state_t to indicate whether MySQL protocol object is allocated, usable or freed. Freed means that memory allocations made by the protocol are freed. That is, command history etc.
mysql_backend.c: gw_backend_hangup and gw_error_backend_event used to call error handling function although session was already closing. Added check for session state.
mysql_client.c: route_by_statement lost some packets in case where query was sent in multiple packets.
mysql_common.c: gw_MySQL_get_next_packet failed in packet handling with route_by_statement. When multi-packet query was merged into one, packet type wasn't copied.
	protocol_archive_srv_command and mysql_protocol_done didn't have proper locking in place which lead to occasional crashes.

server/modules/routing/readwritesplit/readwritesplit.c

@@ -1549,7 +1549,7 @@ static void clientReply (
                         size_t   len = MYSQL_GET_PACKET_LEN(buf);
                         char*    cmdstr = (char *)malloc(len+1);
 
-                        snprintf(cmdstr, len+1, "%s", &buf[5]);
+                        snprintf(cmdstr, len, "%s", &buf[5]);
                         
                         LOGIF(LE, (skygw_log_write_flush(
                                 LOGFILE_ERROR,