move filters to common/filters
re-arrange order of required modules for modelers

This has no functional change … I wanted the requires for
property and unit support to appear in the same relative
locations. Makes it easier to think about how they work.
propertyListener: pass value as arg in callback

Simplifies the code in a listener that usually executes
the following as the first statement in the callback:

  var value = model.get(propertyName);