This is a starting point for a discussion on how to resolve #8
In this PR:
The old 'Epistolary Event' model has been split in two models:
Letter Actions are atomic uses of a letter.
Epistolary Events are collections of letter actions.
A new model 'Case Study' has been added.
More human-friendly texts are shown in the admin forms. For instance: the case study form now says 'Add another Epistolary event' instead of the default "Add another Casestudy_epistolaryevent relationship".
This is a starting point for a discussion on how to resolve #8
In this PR: