graph related functions from Track to QuadGraph,
removed plib usage. The AI is now able to drive
a loop (re-using the same quad, before continuing
on the original path). The beack track currently
defines a simple look at the first right hand
turn (the AI will drive down the hill, then
up again and then keep on going).
2) During the conversion process some AI called
function were significanly sped up, but it has
to be tested if this has any ill effects for
certain tracks or certain karts.
3) Tried to add support for moving sky domes, but
that doesn't work yet.
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/branches/irrlicht@3527 178a84e3-b1eb-0310-8ba1-8eac791a3b58
864c1d6fff