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.
Merge pull request #17 from skysql/session_variable_test

rwsplit router tests for session variables
mysql_client.c:gw_error_client_event & gw_client_hangup_event: added session state check, if session is already closing, don't start redundant call to dcb_close.
mysql_common.c:mysql_protocol_done: added protocol state check. Used not to check it which caused double free of allocated memory.
Merge branch 'release-1.0beta' of https://github.com/skysql/MaxScale into release-1.0beta
mysql_common.c:protocol_add_srv_command didn't check that protocol status was MYSQL_PROTOCOL_ACTIVE and wrote to freed memory.
Fix to bug #463, http://bugs.skysql.com/show_bug.cgi?id=463
mysql_common.c:gw_MySQL_get_next_packet didn't handle case where an insert command followed by alter table in the same read buffer. It shouldn't been possible without multi-statement being set.
Merge remote-tracking branch 'origin/release-1.0beta' into session_variable_test