Added selection of inverse properties that can be added and removed independently from normal properties.
The offered inverse properties are fake at the moment, they are the normal properties.
Step in transition to inverse properties.
Normal and inverse properties now have different colours. (aesthetics not considered atm)
Minor changes in comments and text of 'property-selctors'.
temp
Merge branch 'isOfProp2' into develop

* isOfProp2:
  temp
  Minor changes in comments and text of 'property-selctors'.
  Normal and inverse properties now have different colours. (aesthetics not considered atm)
  Step in transition to inverse properties.
  Added selection of inverse properties that can be added and removed independently from normal properties. The offered inverse properties are fake at the moment, they are the normal properties.

Conflicts:
	app/js/services/availableClasses.js