Added extra space at the bottom of the page.

When removing a filter I find myself re-scrolling to the bottom very often, in
order to see how the document list has changed. This has the potential to annoy
people to death.
Removed unneccessary local variable for comprehensibility.
Changed handler from 'change' to 'keypress'.

The stupid enter key seems to be the same for all browsers (FF-Chrome that is),
and the old way to apply the filter as soon as the field is out-of-focus was
intolerable.
Set form fields to match the removed filter.

How nice is this of me??!?! Because it sure as hell will happen that someone
misspells a word or something and then wants to edit it. On the other hand I
don't need an extra 'edit' button.
Improved type-selection form.

I am a horrible person. No one wants to de-select type after type until only
the one or two of interest remain.
As a bonus, I listed the type restriction as with any other filter in order to
reduce confusion over if the filter is applied or not right now.