Migrate JSkat base module to Kotlin

[b0n541]

Kotlin enables multiplatform re-use of JSkat base code not limited to Android.
Kotlin leads to less boiler plate code that is easier to read.
Kotlin is also more fun.

[b0n541]

One good start would be migration of all events and commands for the event busses to Kotlin data classes.
Another starting point is the big mutable SkatGameData class. This one should be converted into an immutable data class with copy() operations to create the next iteration after a player did a move.