This script is in charge to detect whether the client is compatible with the
game (not being Internet Explorer, having support of local storage and
websockets).
It also manages the theme preference, stored in the localStorage, and displays
the corresponding theme according to this preference.
This page contains currently elements for the intial loading state: a theme
switcher, a play button and links to the privacy policy, the license(s) of
elements reused in the game and legal mentions.
It also contains error messages when JavaScript, websockets or local storage is
disabled, but they are not displayed or displayed properly yet.
