Made tractor beam upgrade work in tablets and added pfx.
Returning failure reason of first attempt in robot.swing(), closes #555.
Merge branch 'master' of github.com:MightyPirates/OpenComputers
Merge branch 'master' of github.com:MightyPirates/OpenComputers into master-MC1.7.10

Conflicts:
	src/main/scala/li/cil/oc/common/item/Tablet.scala