Beta 2

New features since Beta 1:

• Adds a simple minimap
• Adds tooltips with instructions for all parts of the game
• Adds an artifact "inventory"
• Adds the last two bosses
• Prevents "impassable" traps in corridors and rooms before level 4
• Introduces a win state (Dungeon level 20 is your goal)
• Organizes the type of monsters that appear in different levels to make everything feel more coherent
• Monster speech bubbles get some transparency when the player is behind them
• Tweaked colours and amended some typos in various places (Blue is no longer as dark)