initial version
Allow setting github repo url in _config.yml
Add a minimal TODO
Minor correction and tweak to _README
Anoter TODO
Do not link to PDF manual by default

PDFs are bad for storing in a git repository, and most people
won't be interested in downloading this from us anyway. So do
not force package authors to put it onto their gh-pages (they
still can do so by modifying the template if they want; OTOH,
users can download the PDF manual from gap-system.org...)
github actually already sets site.github.repository_url
cleanup
template: specify content type for scripts and stylesheets

While these usually are JavaScript and CSS, it is good practice to
make that explicit.
template: do not use http-equiv="X-UA-Compatible" with "chrome=1"

This is meant to force the Chrome Frame plugin, and is deprecatd.
template: include MathJax by default
update.g: output homepage URLs for package dependencies
template: add hyperlinks to deps, and also list suggested deps
nq 2.5