Add check for no null IIcons on facade registration

Continuation of #1977
Remove landmark's levitation. It's broken physics.
added protection against exception raised
further protection against possible null icons
Merge branch 'landmark' of git://github.com/Prototik/BuildCraft into 6.0.x
Merge branch '6.0.x' into 6.1.x

Conflicts:
	common/buildcraft/transport/ItemFacade.java