Terra Trac script

This is conversion of FS17 script for 3d tracks for your excavators.
This is not a mod. You need to put TerraTrac.lua to your mod and
configure it in your modDesc.xml and vehicle.xml. Everythnig is the
same as in FS17. See readme.txt in zip for detailed instruction.

If you find any errors or issues, let me know in comment or to
[email protected].