Put the rain stuff on activeObject

Part of RFC #36.

### Situation
Rain is a result of a click but the data lives seperate from all other data gathered after a click.

### Problem
In the light of RFC #36 all data is either the result of a click or an aggregation of the extent and belongs to respectively a activeObject object or extenAgg object. 

TODO:
- [x] Rename scope.activeObject to scope.pointObject
- [x] Add rain to this object
- [x] Define rain model in masterCtrl
- [x] Refactor pointObject