Shred's Smoke Mod 1.1.1

1.1.1 changes:

- Corrected the off-track dust to be less bright. This was a careless edit. Apologies

1.1 changes:

- Reduced the .png filesize without reducing image quality. Earlier a non-ideal method of saving .png was used. Improves FPS performance slightly
- Updated tyre_smoke_grass.ini color values
- The backup files from AC 1.5.6

Fixed some (barely visible) roughness around the smoke texture edges + updated the original backup files and readme.txt to match Assetto Corsa's latest version.

Edit: The backup files are from AC 1.3.4 but they are the same as in version 1.3.6.