Entities can be solid, or not; it affects stairs.
Switch from OpenStruct to hashes
Added basic input component. It's still data-driven...
Allow generation of dungeons.
- Renamed startX/startX to start_x/start_y
- Switch map back to class; specify fields
- Separate out initializing systems with entities
- Support maps with minimal fields defined
- Added call to change maps
- Added `Dungeon` class to represent maps
First cut of dungeon generation.
- May need to connect rooms
- Fixed issue with early display termination (nil)
- Added a bit of functionality around maps bigger than the screen