Add conditions for ticket-custom format date

[massimo.b@…]

As mentioned in comment:6:ticket:13216:

There is no way to create a query for "not set" or "not between" in Trac. It is only possible to create query for "duedate between dateA and dateB"…

There could be more filter conditions for the date format like the following. This applies also to core fields like Created and modified. I'm going to create the examples based on the "Created" field:

• Created between 2019-10-01 and 2019-10-25 (already available, just for completeness)
• Created not between 2019-10-01 and 2019-10-25
• Created after 2019-10-01
• Created before 2019-10-01

More easily, taken from my mail clients (Evolution) filter engine, you could just drop the between rule and implement:

Date <Created> {is,is not,is before,is after} <date>

Thus any between-rule would be a done by a set of 2 rules using before and after.