Mining resprite/adjustments.

https://dl.dropboxusercontent.com/u/16913760/bay/turfs_nomeson.png
https://dl.dropboxusercontent.com/u/16913760/bay/mesons.png
https://dl.dropboxusercontent.com/u/16913760/bay/ores4.png

- Resprited mining asteroid turfs.
- Resprited most ores (didn't touch diamond).
- Moved ores to an overlay rather than a distinct turf sprite.
- Added surface deposits of platinum and coal to the asteroid.
- Slightly adjusted surface deposit numbers.
- Changed phoron crystals to a compression product instead of a smelting product.
- Poorly resprited the terrible codersprite crystals in obj/mining.dmi.
- Added a crumbled-edge overlay for asteroid edges.
- Changed glowshrooms to be a bit darker and more colourful.