Removed Corium Assets

Removed leftover assets for Corium
Fixed Double Door Textures

Fixed the way textures are applied so that doors from our mod can appear
as double doors. Renamed door textures to be consistent with Minecraft
door textures. Got rid of a few obsolete textures. Unfortunately,
something broke with door blocks updating. I need to fix that in the
next commit.
Fixed Door Bug

Fixed the bug referenced in the previous commit that caused doors to
break instantly.