Compatibility for 1.39 Beta version

Changelog v3.7.1 for 1.38 and 1.37 version:

- (FMOD) Added "Sound level-transition of rain hitting in the cabin"
- Minor tweaks & values for some textures, windshield effects...
- Improved "outside" Rain texture
- Others

Deleted "dirt.tobj" file (not necessary) most compatibility with other mods

- New texture raindrops created by me
- Some tweaks for windshield effects

v3.6 for 1.38.x:

- New texture raindrops for windshield & windows (Thanks to AleyxeP for main texture)
- Reworked ("exterior") rain texture & values for 1.38 version
- Fully reworked values for windshield effects
- Increased number of raindrops
- This version will use the old particle/spray effect of the wheels, better compatibility with other mods and better performance.
- Added some new thunders sounds
- Equalized and tweaked the delay of thunder sounds

*Note: Thunders will be heard in an interval between 1.5 to 5 seconds when seeing the 'flash' (lightning), simulating distance as IRL

The number of raindrops on windows will vary depending on the intensity and the direction of the rain

v3.5.2
- Fixed smoke effect (Chimneys, factories etc ...)
- Improved dirt/smoke particles of wheels
- Other minor adjusts (windshield effects and water particles)
- Improved some thunder sounds

- Rain textures Rework
- Tweaks values for Rain textures
- Minor adjustments values for water particles/spray

- Minor tweaks: windshield effects
- Water Particles/spray improved