Flags updated

[Stan Shebs]

I've just committed a major overhaul of the flag images.  The biggest
change is to the larger (16x16) images, which are now mostly scaled
from large flag images (as seen on the very helpful Flags of the
World site, http://fotw.digibel.be./flags/ ) and thus look much
more like the real thing.  I've also tweaked colors, and in a few
cases, updated the flag to reflect a change in the country's flag
since these images were last updated several years ago (Afghanistan
and South Africa being two notable examples).

Although in general this change shouldn't have any bad side effects,
the images do need more colors to make all the anti-aliasing work,
and someone on an 8-bit display may get some unfortunate color
choices.  If this is a big problem, I can try to work up some sort
of color-impoverished fallback.

Stan