Texas Motorspeedway Update

Hi people. An updated version of Roman Mika's Texas Oval: full credits to him, of course.
What's new:
- fixed a few missing objects (part of the grandstands and of some buildings);
- new grandstands;
- new trees;
- new Md file (CC setup and tyre consumption).
As usual, the MD file is set to fit the original Gp3 1.13 physuc and performance file (800 Bhp, 16384 as max CC grip...): you can modify the MD as you like to fit your physic and performance.
Hope you like. As always, report any bug.
Claudio.