General comments on the schema

I will use this issue to add some comments on the relationships between our two schemas.

1. First of all: @zfletch : could you please add some examples in the description of the schema (on the future django one)? Most of the tables are obvious, but some of them are not (i do not understand the function of "viewer" for example, or "PassagePassage", or the difference between "writer" and "author").
2. I think it is important to consider the possibility of having many "versions" of a text (what you call "passage" and not only translations. This because one can have many versions of the original greek text. So I would prefer the idea of versions then translations.
3. I think we should have something like "edition" allowing to specify the source of a particular text (or translation or version...). We need a very broad concept of edition which could refer to an existing edition ( a published one, for instance) or to the fact that a text, translation or version is created by a lab or a person.
4. I think - as discussed - that we would need a language table - with the possibility of adding as many language we need
5. Comments are the same as our notes, I guess. It should be usefull to be able to link them to anything (a Paggage but also a version or translation). AND it should be usefull to be able to link them to a specific word (just with a word number, for example)
6. Status: we could use it also for a validation purpose? Or we should create anothe field. Example "translation validated by the PR..."
7. Work: I think it could be useful to have a field for a specific "book" of a work (ex iliad book 3 or AP book 5 etc.)
8. URn: We would like to have the possibility of adding many URI. So a URIS table would be usefull (with different sources of authority)