GSC Wetter Modifikation

The new weather mod from GSC is co-authored with Piva.

- there is no exposure;
- the climate for Mexico and Dalton has been adjusted;
- New day / night skyboxes;
- smooth transition between climates;
- the color rendition has been redesigned;
- the lighting package from Piva is turned on - old flare files are corrected

Test on 1.6.x, 1.28.x