-Added calling assembly GUIDs to chat command register/unregister

-Added OnCubeGridLoaded event
-Finished implementation of MergeBlockEntity and PistonEntity
-Started implementation of RotorEntity
-More work on RotorEntity
Merge branch 'master' of https://github.com/SEModCommunity/SE-Community-Mod-API
Merge remote-tracking branch 'upstream/master'