mysql_mon.c: Added back server state logging to Debug build.
query_classifier.cc: removed some extra debug code, cleaned up a bit function documentation.
mysql_client_server_protocol.h, mysql_backend.c, mysql_common.c: changed some variables to signed ones to enable checking of calculations in the code.
skygw_utils.cc: removed erroneous debug assertion.
When MaxScale starts it opens log file of each type and if there exist log files of same types in the same directory, it will try to reuse the file with largest sequence number in it. If there are no existing files, a file name with sequence number 1 will be created. If the file with largest sequence number is not writable, a new log file with larger sequence number will be created.
log_manager.cc:
Log manager handles cases where there are mismatch in user privileges.
Mark log files enabled in the global lm_enabled_logfiles_bitmask after initialization so that it reflects reality in error cases. In general, take into account the possibility that any phase in initialization may fail and read return values.
Replaced file_exists_and_is_writable to check_file_and_path which has a slightly different logic and which detects if file open fails for a few different reasons.
Improved logging (in stderr) in general in error cases.
gateway.c: Also check home directory accessibility in case when it is provided as a command-line argument. Added function check_dir_access to provide that function. Read return value of skysql_logmanager_init and exit (nicely) if it failed.
skygw_utils.cc: initialize mlist with version number 2, which indicates that object is initialized (different than zero) and that there are no active updates on the object (version%2==0).
query_classifier.h: added parsing information structure to query classifier away from buffer.h.
buffer.c:introduced a buffer object which includes object pointer and a clean-up call-back function. Buffer objects form a list which is cleaned up by the last referrer of the buffer, as a part of gwbuf_free. Buffer object list is protected by a spinlock gwbuf_lock.
Also added identifier type, bufobj_id_t which is enumerated type and currently includes one value only, GWBUF_PARSING_INFO. Added also a bitfield for information about the buffer. It currently has one type only, GWBUF_INFO_PARSED indicating that buffer content is parsed and there is buffer object of type GWBUF_PARSING_INFO.
skygw_utils.cc:replace_literal:changed regexec matching to case insensitive because user-defined literals are sometimes converted to upper-case ones.
