adjust `lockOrientation` because to avoid Firefox throwing a `TypeError`
fix modal-closing logic
create hosted Firefox manifest for controller as a web app
begin hooking up gamepad to Commander Keen game
add nice icon for controller
gracefully handle client disconnects; spruce up event listeners and overall greatness here and there (fixes #82)
add verbose comments explaining steps (issue #84); rename `_handshake` method to `_pair`