Next iteration: csv color definition files, docs

Expand docstrings, make imports explicit, use csv instead
of custom color definition format.
Separate add_colors/add_colors_from file

Also fix sphinx doc generation.
Remove ability to pass a mapping to find_nearest()

The same can be achieved by creating a color system
with the desired color definitions. Makes the API easier.
Minor documentation modifications
Use the same version string for setup.py and docs
Minor docs changes and restructuring
Added LICENSE.txt, rudimentary README
Added GPL2 headers
Try to fix compilation errors on readthedocs.org
Next stab at fixing compilation errors
And again: Fix compilation errors on readthedocs.org

This time we mock colormath
Tiny corrections
Avoid importing tint in docs/conf.py
Changes in the hope to get autodoc working.

On readthedocs.org, that is.
Special-case rtd in setup.py

Ugly, but if it helps ...
Tiny change to try and please rtd.

Please! Pretty Please!
OK, some more poking around.
Sorry for the churn.
More stabbing in the dark.
OK, this might be it.

I'm feeling stupid now.