Flagged patrons: enhancements

(Biblibre - sponsored by Université Lyon 3)

In 3.2 when a patron is manually flagged using gonenoaddress, lost or debarred, it's just managed as a toggle choice.

Enhancements proposed are:

• add a comment field to the current 3 choices: e.g. debarred_comment
• change debarred field from tinyint to timestamp: entered through the UI

If timestamp == null, patron has never been debarred

If timestamp >= NOW(), patron is debarred

If timestamp ⇐ NOW(), patron not debarred anymore