refactored GUI by making an own GameGUI class

put the GUI operations of the planet in the GameGUI class
put some of the GUI operations of the player in the GameGUI class (more
to come)
added action denied overlays to the GameGUI class
refactored Player

used Timer for credits Up
refactored Player

put cooldown visibility into the GameGUI class
renamed Interactive to Action since it better reflects its purpose
added cooldown timer to Action