v0.2.3 - Tutorial, Player auth

Finally, the "first" stage is now acting as a proper tutorial! Still haven't worked out a system to add more stages, but now it's a bit easier to start the game! Here's a full list of things done:

• The UI at the starting screen has been divided up into scenes, making it a bit easier to give the user feedback for his actions, but the system could use some improvements.
• Starting stage has been expanded upon.
• A new button prompt system makes itself known to help guide players through the currently available controls!
• The checkpoint system has been iterated upon to support multiple checkpoints per stage!
• Player movement has been tweaked slightly (need more feedback on that)
• A new audio track for the spike trap.