Changes:

* Added convenience methods for client/server synchronized shape recalculation.
* Added convenience methods to AbstractPart for redrawing and recalculating shapes on the MultipartContainer.
* Made PartContainer redraw and recalculate its shape after a rotation/mirror/transformation, as this should pretty much always happen.
* Fixed issue where blocks being converted to multiparts would break blocks depending on them.
* Added ability for parts to have custom side-solidness shapes.
