More Rural & Forest Tileset Fixes

Though I doubt there are a lot of people who still play NWN1 when the second part is out, I decided it wouldn't be the best decision to keep this only for myself.

These files are not a haks but more of overrides, as originally they were supposed to be used to enhance the picture on a hakless PW.

Myself, I've added them to bioware bifs using BIF packer/unpacker v1.0 by Ganymed to keep my override folder empty for other experiments.

The idea for both packs was rather simple and popular. The first of them, ttf01_foliage, adds branches and foliage as well as slightly modifies the trees models in ttf01. I can't say that it's better than any previous attempt to do the same with bioware forest, it's simply my modification.

The second, ttr01_grass, replaces the cobblestone with grass in XP2 city tiles for ttr01. I made it because I was unable to find a hak which fixes not only the models but both the walkmeshes, in order to make the grass grow where it should and the footstep sound like the character is walking on the grass, not cobble.