* Separated out rivers and bridges into its own file with three map variants
* fixing tags
* removed extra 4 starting positions from the medium map since it only supports 8 players
* update GetUnoccupiedPoints to consider hazards with a flag
* use new utility method to fine unoccupied points and enforce map sizes
* changed up casting to make IsAllowable() more usable
* change map support for large #'s of snakes
* test square board fn
* format comment
* add whitespace
* better support large #'s of snakes on small boards
* include an intermediate xlarge size
* allow initial food placement for 8 snakes on 7x7
* fix logic to be for small board
* fix inverted logic
* logic should be actually <= 4 snakes, not 7
* reorganize code
* first draft of map generator interfaces
* add explicit random interface to board helpers
* implement standard map
* rename Generator to GameMap
* allow initializing snakes separately from placing them
* add random number generator to Settings
* updates to GameMap interface
* add helpers for creating and updating BoardState with maps
* extract board generation out of rules.Ruleset
* update comment and remove redundant interface check
* clone boardState in constrictor to respect the ModifyBoardState interface
