Merge branch 'entity'

Finish implementing most methods in base Entity class

Update to SpongePowered/SpongeAPI@1ceca6eb19997567d632f421ac1fecf12e6cd993

Fix compile errors caused by submodule update

Add converter to all classes in entity package

Update to SpongePowered/SpongeAPI@6281cfc5daf3b38fac6f720cc0427aab1711aba5

Refactor TypeConverter and fix compile errors caused by submodule update

Finish Converter children maps (unit tests fail at the moment)

Fix type mapping issues which were causing tests to fail

Begin implementing entity package

Implement PoreEntity through PoreItem

Implement PoreItemFrame through PoreLivingEntity

Implement PoreOcelot through PoreSlime

Implement PorePig through PoreThrownPotion

Implement remainder of entity classes