a demo after T seconds of idle time, --demo-tracks a,b,c
to specify a list of tracks to use for demo mode, --demo-karts
to specify the number of karts.
This is WIP, esp. it crashes if ESC is pressed during a race
(other keys will successfully return to main menu).
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@11189 178a84e3-b1eb-0310-8ba1-8eac791a3b58
