Optimize Icons Compression

[edo0]

I have run the Paper icons folder through optipng (using this tool called minuimus), and realised that almost all icons are not encoded with the best compression, which should impact loading time especially on older systems. Gains were from on average between 4% and 30%, but for some icons even up to 50%

Some examples

I think there may be a benefit in applying this directly on the repo contents.

[txtsd]

I personally run images through pngcrush first, then oxipng which is basically a multithreaded optipng.