Changes

Summary

1. Register the mechanical arm so it will save and load properly. Also (commit: 8b04699) (details)

Commit 8b0469969bf84a4fe062295010af56976b4fc747 by AlexIIL Register the mechanical arm so it will save and load properly. Also fixes #3212 (commit: 8b04699)
	buildcraft_resources/assets/buildcraftcore/models/block/engine_on.json (diff)
	common/buildcraft/BuildCraftBuilders.java (diff)
	common/buildcraft/BuildCraftCore.java (diff)
	common/buildcraft/core/network/EntityIds.java (diff)
	build.gradle (diff)
	common/buildcraft/core/lib/render/FluidRenderer.java (diff)
	common/buildcraft/builders/EntityMechanicalArm.java (diff)