[r1] Minifix and playing online

Changes:

• Fixed it being possible to start the game with only 1 player, despite what UI says.
• You can now switch to/from fullscreen by pressing Alt+Enter.
• Fixed diagonal floor discs having odd hitboxes
  (which is hopefully the only bug caused by GameMaker Studio 2.3.1 beta randomly discarding external changes to files)
• Fixed compatibility with GMTogether (more on this in a moment)

Playing online:

I have included a special version of GMTogether that I hot-fixed to be compatible with GameMaker version that the game uses.

This allows you to play the game over internet, and also both players to use their own mouse+keyboard when doing so.

To use the tool, extract both the game and GMTogether-for-BBB somewhere, and then drag-and-drop the game's executable onto GMT-Launcher executable, like so:

After doing so you will be presented with a small menu that allows you to host or join the game by IP address.
Standard rules apply (port forward or use a VPN service; make sure the game is allowed in Windows Firewall).