Various fixes for Gorge & Thunder Mountain

Gorge:
-Fixed broken geometry on blue and red side.
-Fixed hole in out of bound area on blue side.
-Added clipping to mutliple areas.
-Removed Collision from multiple props.
-Fixed stuck spot.

Thunder Mountain;
-Made blue side reflect the team colours more.
-Added Clipping to multiple stairs.
-Fixed Missing texture.
-Fixed clipping on some stairs.
-Fixed Red sign on blue side.
-Fixed Blue sign on red side.