rockpaint.c: Paint plugin for color LCD targets. Features include: different tools...

rockpaint.c: Paint plugin for color LCD targets. Features include: different tools (brush, bucket, cut/copy/paste, line, bezier curve, text, rectangles, ovals, linear and radial gradients), 18 color palette, RGBHSV color picker, BMP file loading and saving. This still needs some work (and maybe some, if not a lot, of cleaning up of the source code) but it works fine (tested on h3x0 and ipod5g sims and ipod5g real target).

viewers.config: add rockpaint to the list of available viewers for .bmp files

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10258 a1c6a512-1295-4272-9138-f99709370657