Complete rework of the BMP loader: * Support for 4 bit, 15/16 bit and 32 bit BMPs in addition to the already supported 1 bit, 8 bit and 24 bit formats. * Better protection against corrupt BMP files. * Added dithering for 2 bit targets. * Optimised, compact code. There's almost no code size increase for SH1 (only 68 bytes), and even a decrease for coldfire, with all the additional features. * Code policed. * Fixes bug that loading a backdrop worked only once per session.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11548 a1c6a512-1295-4272-9138-f99709370657