Removed shouldSideBeRendered from the client proxy, and updated EntityCausticBoat.
TNT is fixed.  However, this means removing all the EntityRegistry.getGlobalUniqueEntityID references because it's broken.  Time to bring back the entityId config options?  -.-
Alright, entity id stuff is now well and truly fixed.  Also, the caustic boat is *sort of* fixed.  Not completely, but it's at least somewhat usable now.