Absolute splendour

Are you ready, really, really ready?

Introducing:  a massive graphics update. Now you can have custom
textured entities by implementing the base class
RenderEntityProjectileBase. Also, in init/ModEntities/init(), all
entities/render methods must be declared. Also, now carrot ammo can be
exploded by right clicking. Finally, unmentioned in previous commit,
entities now explode on contact with EntityFlyingCarrot.
Removed old entity icon

Removed old entity icon in favour of the new renamed version.