Allow date filtering of before and after a given date

[drewthorp]

As a user I want to be able to filter on before or after a date as well as on a date or between a date range.
Because I want to be able retrieve all unprocessed records before a given date (The after is just for completeness).

• It's done when wherever you can use on <date identifier> or between <date identifier> and <date identifier> you can also use before <date identifier>.
• It's done when wherever you can use on <date identifier> or between <date identifier> and <date identifier> you can also use after <date identifier>.

[timgentry]

For maximum flexibility, you should also be able to use before <date identifier> and after <date identifier> and after <date identifier> and before <date identifier>