GD and JPEG: who needs 'em?

I've removed the final dependencies on the GD and JPEG libraries. This is convenient because many shared PHP installations aren't configured with the JPEG library and it's not always easy to add it in.

We now depend on the NetPBM package for all graphics......which can easily be installed in your home directory in a shared environment.

This change will appear in 1.0beta3 when it comes out. If you don't want to wait, you can pull the latest code out of CVS and start using that today.