Updated Gilles75's Reims track 1.0

added grassfx (grass texture copied from osterreichring)
add ai_hints and updated boundaries to prevent cars running wide during overtaking

Note: when downloading the reims track, it seems there's a 67 and a 66 version for it (one from RD, one from another site), and the fast_lane.ai got mixed up during installation, so I also put it in the file, not my work.

I can't add grassfx for corn fields, some grass simply grows in the air.