Added test_lib::timer() function for timing tests.
Added entity_record_limit_dao::_set_delete_limit_cache_lists_multi()
Updated cache_driver::list_remove() to accept an array or a single entry of keys to remove.
Removed entity_record_dao::_by_fields_select() as well as supporting functions from record dao drivers, since this function does not belong.
Fixed bug in cache_lib list_add and list_remove batch operations... PHPRedis has poor support for a valid redis call (adding/removing multiple values to/from a list in one operation).
Corrected bug in cache_lib::multi's $after_cache_func execution. It was not passing the correct array of cache keys and values.
Simplified the entity_record_limit_driver class by having it extend from the base entity_record_driver classes, this way they can use the standard by_pk, by_pks, insert, update, delete etc etc functions.
Finished entity_record_limit_driver_mysql by adding by_fields_offset_multi().
Created entity_record_limit_driver_mysql class, not yet tested.