Add Keyboard Support

Added a simple keyboard interface: WASD or arrow keys to move, hold Shift to run. Also made Spacebar and Enter emulate mouse click (Useful for conversations, but also nice if you don't want to ever click ever). Since certain parts of the game (Like searching with Rarity's special ability) are heavily mouse-based, I opted to leave those as they were. Ideally all keys could be customizable, but to do so well would require an ingame menu of some sort, and I don't have time/energy.