Simplify running steps

[cxong]

The game requires running a python script to extract sprites; this is a bit cumbersome and it would be better if the game could read directly from game data files. Further from this, the game should be able to read as much of the game's data as possible - the data files are quite well documented at https://moddingwiki.shikadi.net/wiki/Crystal_Caves

• [x] Read sprites directly from game files, remove python script
• [x] Auto-detect game installation from steam/gog, or failing that local directory / command line arg / envvar
• [ ] Read game levels (remove JSON dependency and hard-coded JSON level)
• [ ] Sound
• [x] Image files
• [x] Font and icons