v0.9999

A few small bugs required fixing. But subsequent playtesting had me fixing other issues and adding features.

• BOL answers the lack of a lob-style shot for the player, it falls upwards. If you get a feel for its range it's quite useful.
• RUG spreads out into a wide mat when it hits the floor. You can also stand on it, allowing you to extend a platform for longer jumps.
• WAH stops on the floor, then lobs as many bullets as you have hearts empty.
• A clock describing the current mode and level you're on has been added to the UI (bottom right).
• Boss chunks have a chunk with 2 altars before them, but they can disappoint when they don't offer new shots. A new type of chunk with a single altar and coin has been added. These replace the standard bridge chunks  before boss fights.
• Mobs overlapping has been bugging me for a while. Now they use a system I've used in other games: Busy tiles. When a mob acts it marks its tile with the current time. If another mob wants to act in the same tile it has to wait until that time code is a second in the past. This means that overlapping mobs like rollers will come at you sequentially instead of a lump like they did before.
• A death prompt has been added to hardcore mode when you die, to help reduce the shock of restarting at level 1
• More chunks (Q.E.D.) and bug fixes.