* add utility methods to Editor and BoardStateEditor
* add Meta.Validate
* allow setting Meta.MinPlayers to zero
* remove uints in map sizes
* use Meta.Validate in HazardPitsMap
* 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
