[game-api] General improvements to game API

  * Move `send_msg` to lightgames.py as a static function
  * Add `send_lamp_multi` for sending an array of lamp changes
  * Move JSON decoding of messages to webserver.py
  * Remove all dependencies on `tornado.escape` in game modules & queue
[game-api] Add `on_enqueue` handler to game API

  * Also, separate incoming messages between the game and queue modules so
    that each module only has to deal with messages designated for it
[templates] Organise game & game-config template files