* add 'map' cli command
- provides the following map information functions:
- list all available maps in the global registry
- display map metadata
- update docs with map command examples
* add list and info subcommands to map cli command
* rename map command list and info factory functions
* add --all flag to map info subcommand
* handle cmd.Help error
* remove squad support and switch to using pipelines only in RulesBuilder
* remove spawn_food.standard from legacy ruleset definitions
* bugfix: Royale map generates Standard food
* add maps support to CLI
* add automated tests for all registered GameMap implementations
* update README
* 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
