MxSxC1 Weather Sleet

Thinned out rain, fixed tiling, removed alpha channel, and now looks way better and less intrusive.

Reduced size of few snowflakes and removed alpha to make work better with some shaders.

Something has changed with Iris, and this is not working as well with some shaders as before. Not getting the "sleet" effect on some shaders, or snow is just too transparent. Working on fixes to balance.

No longer working properly with Astralex in particular (again seems to be alpha channel), and a couple other shaders. Working on fix for it, need to test with later version...