Tweaked and cleaned up slot highlighting a bit, also made it available in robot GUI.
Returning number of crafted items from crafting upgrade's `craft()` as second result (this is the stack size of the result). Closes #561.
Merge branch 'master' of github.com:MightyPirates/OpenComputers into master-MC1.7.10

Conflicts:
	src/main/scala/li/cil/oc/client/gui/DynamicGuiContainer.scala
	src/main/scala/li/cil/oc/server/component/UpgradeCrafting.scala
Fixed a massive game-breaking bug of epic proportions [/sarcasm].
Merge branch 'master' of github.com:MightyPirates/OpenComputers into master-MC1.7.10