Fix for player jump height

The player stops ascending now when the spacebar is released
SpriteMap Japan Update
Better implementation for moving platforms

The player now only is dragged along by horizontally moving platforms.
Before he was sliding of of vertically moving platforms.
Adjusted Acceleration and Maxspeed

Adjusted the values for acceleration and max speed to make them match
the defined values in the GDD
Restored Editor and Credits button
Handling of arrow visibility in world selection

The arrows to change the current world now are only being drawn if there
actually is a world to change to.
Fix for vertical and horizontal jump platforms

- added the handling for jump platforms
- changed the way the jump formula is calculated and the values are used
- added a new method which determines the needed enum values for the
movement
Implementation for switches

- Completely refactored the code for how switches work
- added an interface which needs to be implemented by all objects that
are supposed to interact with switches
new gitignore