Version 0.3 released

Bit of an overhaul:

• Added a menu screen so you can skip the tutorials (BTW the "Settings" option doesn't do anything... yet).
• Played around with the graphics (particularly the tiles for the dungeons), still based on the Kenney.nl assets but I've tweaked them a little.
• Increased the playable area, so should be able to do larger levels.
• Add some animations to the background, to bring a little life to the world.
• Some behind-the-scenes refactoring.