Pegbox - new graphics for Archos, c200, small H10, Mini, M3 - also cleaning and small...

Pegbox - new graphics for Archos, c200, small H10, Mini, M3 - also cleaning and small tweaks to the rest of the greyscale and monochrome bitmaps. Aspect ratio correct the pieces for the Archos screen (now uses 9x7 tiles) which made it possible to also add the header with statistics). Necessary changes to pegbox.c: don't assume piece height = piece width, prepare a new 'wide' layout for the c200 with the statics at the side. Additional cleanup - make the code more readable by replacing repeatedly used bmpheight_XYZ with defines, splitting some too long lines. Let the 'Start on level' line in the menu actually appear on the Mini's screen. Also rename the greyscale graphics according convention to '...x2.bmp' and set the mime-type more accurately for all pegbox bitmaps. Finally, add Joel Puik, the creator of the original colour graphics to CREDITS.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18803 a1c6a512-1295-4272-9138-f99709370657