removing jpeglib from svn

[Jamie Wilkinson]

I've got a patch at bug#2408, which builds, but I haven't yet had a chance
to test that it doesn't crash -- I plan on doing that tonight, but if anyone
else wants to grab it and try it, feel free to do so and complain that it
blew up.

I took the memory buffer code from various examples on the internets, it
appears that the original jpeg loader code was also clagged from example
code, based on the comments in LoadJPG :)  I welcome comments on the
readability and quality of the new functions, because I'm not totally happy
with it :)

Also worth mentioning: the code has a SaveJPG function and support functions
including jpeg_start_compress, and jpeg_write_scanlines, which seem to be
the only reason for needing the define of JPEG_INTERNALS at the top.  Does
quake3 actually need to write jpegs?  I haven't looked to see if SaveJPG is
called from anywhere else, but I would have thought that file transfers from
a game server don't decode and require re-encoding of texture data.  I'm
going to bin this later if I find it's not necessary.