Add Inverse option

[MagooChris]

There are Triggers like IsEqualTo and IsNotEqual to, but we have others like IsNullOrEmpty but not a reverse. Maybe it would be better to standardise all of these and have a bool property on each that says if you want it normal or reversed?

Right now I want to goven two states, one on when somthing is null, the other when it's not null...

[MagooChris]

Thinking more about it, maybe just a ReverseTrigger that takes an ITriggerValue might just do the trick and be simpler...