Make Label rotatable

[John Sundell]

You should be able to rotate a Label using the same API that you can use for actors. Functionality like this is implemented in a protocol oriented fashion, so all that needs to be done is to make Label conform to Rotatable. See Actor's implementation of this protocol for reference.

[Krzysztof Kapitan]

I'll take it if it's still open :)

[Jussi Ronkainen]

I was just to about to finish this task also. :)

[John Sundell]

Fixed by @jussi80 in #156 🎉