Implement better cuts and filter dialoge

[pudo]

Currently, filters can only filter on precise values, not on text searches, or simple math formulae like "greater than", "smaller than". I would like to support such filtering, but the backend doesn't have such query flags, since it's focussed on allowing pre-aggregation. We would probably need some support for this upstream, even if via a plugin to cubes.

Imagined operators:

• cut=loan.age:>40
• supplier.name:~Booz Allen*

Any thoughts, @Stiivi?