* A couple of misc comment typo's
* Added missing $CFG required global in file_lock_factory::is_available
* Removed unused $CFG global from file_lock_factory::get_lock
* A couple of trivial phpdoc tweaks
* Removed unused $DB global from postgres_lock_factory::get_index_from_key
* Added global namespace \ to exceptions in get_index_from_key (tested and found they didn't resolve)