Git submodules are great to keep track of themes without having to manage them all in one repository.
But cloning the main repository only gets you empty folders for the submodules; an additional init is needed.
It's easier and more convenient to just clone the main repository recursively, in order to pull in all themes.
I have written explicit instructions explaining to inexperienced Pelican
users what must be done to use the themes in this repository. Changing
the theme is the first thing I wanted to do after running the quickstart,
but it took me a while of googling and reading existing Pelican
documentation to figure out the (in retrospect, obvious) change I needed
to make to my pythonconf.py.
