Remove some image slack to lighten up the installation?

[michaelherger]

@ralph-irving - while working on the grid skin I found there's a lot of slack in the skins. Lots of the images are replicated even though they're not even used or required. And pngcrush etc. could squeeze out a few more bytes. Shall I do some clean up work to make this package light again?

[ralph-irving]

Michael, yes please feel free to cleanup whatever you deem appropriate. Thank you.

[ralph-irving]

File cleanup complete.