Gfx changes for mod selector
Replace modselector gfx, part 1

Icons made by Frances Fawcett. Download button based on work By EntiteFred.
(Via http://www.bit-blot.com/forum/index.php?topic=931.msg10207#msg10207)
modselector: Clean out some old code, add support to open URL via webbrowser.
Merge branch 'modsel-cleanup'
Let's better keep SDL 1.2 the default until everything settles and mac bins are up.