Compatibility update + more

Added support for thumbsticks, as at times Windows treats D-pads as thumbsticks.

Added experimental code to have the Steam on-screen keyboard open automatically when text entering is requested (totally untested due to lack of a Steam Deck; chances are it will not work, as the game is completely software-rendered; feedback welcome).

Reworked assignments of the kind *p++ = ... *p ... (as they are miscompiled by some versions of gcc).

Fixed (server side) registration for hiscores / hiscores receiving and added SITE.PORT configuration option for future use.

Improved/updated manual.