Fixed the used_fatigue field on the character model in models.py
added its appropriate default
Added the __str__ method to various models in models.py
added the Character form to forms.py
Added a bunch of docstrings to models.py
fixed queries for derived fields of the character model in models.py
Make pylint happy.

Clean up module `models` so that pylint is happier. The majority of remaining
complaints are about missing docstrings.
Merge branch 'master' into branch 'character-ui'

Both branches contain useful changes to module `models`.

Conflicts:
	apps/gurps_manager/models.py
Make pylint even happier.

Fix up module `models` again. The previous merge introduced a few quirks that
pylint did not like.