Try to standardize the way we handle tools, materials, digtimes.
- Levels start at 1 and work upwards.
- Level 1 is for "hand" or "primitive" tools.
- Levels 2+ are wood, stone, metal, etc.
- Link dig times, tool levels, and durability together.
- Material groups now define standard "base dig times" which
are the main thing that makes e.g. stone harder to dig than dirt.
The speed of digging almost everything will probably have changed,
in some cases not for the better; much testing will be needed.
