Grassy canyon 7

Fixed version. i have apparently corrupted the stock tree piece on my client,so i decided to replace the trees with my custom one. well, it likely doesnt happen on other computers but meh..
fixes:
*flickering on grass to concrete.
*the uppermost checkpoint which doesnt always work. you will probably fall through the map there now but im not expecting anyone to respawn there so whatevs.
*tweaked finishline.

(The old one will be removed).

i will probably tinker with this one later as my idea of clipping lots of blocks into eachother has proven to only add up to more flickering.