Adding test for `\data\Source`. Refactoring classes in `\data` into "entity" and "set" classes. Split `Document` into `entity\Document` and `collection\DocumentSet`. Renamed `\util\Collection::$_items` to `\util\Collection::$_data`. Constructor parameter in all subclasses is now `'data'`, to provide more consistency with entity classes, etc. Changed `\data\model\Query::binding()` to `\data\model\Query::entity()`, to better  reflect design.
Adding test for `\data\Source`. Refactoring classes in `\data` into "entity" and "set" classes. Split `Document` into `entity\Document` and `collection\DocumentSet`. Renamed `\util\Collection::$_items` to `\util\Collection::$_data`. Constructor parameter in all subclasses is now `'data'`, to provide more consistency with entity classes, etc. Changed `\data\model\Query::binding()` to `\data\model\Query::entity()`, to better  reflect design.

datachand/lithium,mehlah/lithium,jails/lithium,wbeater/lithium,davidpersson/lithium,mehlah/lithium,whowgames/lithium,muyehub/lithium,whowgames/lithium,jails/lithium,pixelcog/lithium,qoqa/lithium,UnionOfRAD/lithium,m4rcsch/lithium-core-library,SensCritique/lithium,qoqa/lithium,davidpersson/lithium,graphis/lithium,UnionOfRAD/framework,pixelcog/lithium,UnionOfRAD/lithium,datachand/lithium,m4rcsch/lithium-core-library,m4rcsch/li3_framework,graphis/lithium,wbeater/lithium,muyehub/lithium,SensCritique/lithium