* add minimal support for serving a game to the board UI
* refactor into new board package
* support reporting errors and author names to board
* support passing an alternate board URL
* avoid using IPv6 for local URL
* use rules.Point instead of a custom Point type for board package
* use zero for generic communication error code in cli
* rename createGameEvent to buildFrameEvent
* tests for conversion from boardState/snakeState to game frame
