performance: changing the order of conditions

Aurora_JSON::from_model giving priority to scalar values,
as most of the time model properties are scalar

Also giving priority for conditions with instanceof (it's fast)
Performance tuning for Trait_Aurora_Data_Map::map_retrieve

Save the value of Au::db()->prefix_table_dot($this) to
$this->prefix_table_dot
performance tuning Trait_Aurora_Data_Map map_retrieve
fix bug: factory Aurora