Updated documentation

I Have started documenting gsl modules and adding more examples.

The module documentation is generated from the gxl files into a subdir in docs
and pulled into the README.txt with the .pull command.

Also, I'd like to bring back the pdl file so I can regenerate the documentation files.
I have a few old ones kicking around.

This is a work in progress so feel free to hold off until it's all done.

Thanks!

-Gyepi