Added automatic server_url detection on B.init().
index.html: emoved "switch player" button.
index.html: cleaned up some unused css rules, renamed canvas0 to container.
Replaced start() with set_status().
index.html: added #overlay and #m1.
Added overlay_message() and some status messages.
index.html: changed default font to Arial.
index.html: added input style for #overlay.
Added a more informative "game_created" message.
Added an error message when trying to run the game locally.