This introduces a new helper to place better mines.
It generates a # of metal mines scaling per player, and generates fairer mines by:
- laying the mines farther apart
- plopping a few clusters or 2/3K mines instead of just 5K mines.
- scaling by # of players so 4v4 has more metal
- Having slightly more mines overall to have a slightly fairer distribution.
The expected metal is around 40K on 1v1 Small, and 140K on 4v4 Medium.
There is a bit less Stone than Metal.