Series and versions

[eevee]

Artwork is frequently a part of a linear series, or one of several revisions. Both of these should have first-class support.

Looming questions include:

• How to depict these in watchstream, gallery views—surely a series should only appear once, right?
• How tags and comments across versions would work—comments may lose context if shared, content tags would be the same but medium tags would not, etc.
• How to add to a series or add a new revision, without sucking
• How the schema should look
• How to handle a series that spans multiple artists

I believe that editing artwork (i.e., uploading a new file to replace an existing one) should create a new revision, unless explicitly asked otherwise.

addendum: It would be pretty cool to support appropriate diffs between revisions.