generator.categories is now a list of (category, articles) instead of a dict. This
is to avoid using ordered dicts that have been introduces in python 2.7, so we stay
as much as possible compatible with older versions.
This fixes#62. Thanks to Bruno for the report.
Added some more notes about how this is working on the documentation. I do think
that the overall structure is clearer now, and easiest to understand. After all,
that's how it should always be !
--HG--
rename : pelican/processors.py => pelican/generators.py
rename : pelican/generators.py => pelican/writers.py
