Starting to add new features

This is my first major uptade to the game.

I have now given the shop a completely new look by creating a new theme and only adapting it to my current editor theme.
I decided to only choose the one font so that there is less confusion.
Instead of +20 speed for the player there is now +5 speed for 5 coins. The same applies to our blob (slime) in the negative range.
In addition, the paths back to the menu and directly into the game now work. (In  the Godot Engine the code for changing a scene looks like this:  get_tree().change_scene("res://Game.tscn")