Deal with some todos

So here is a small fix for the two TODOs. I use a lightweight convertUnits function for that. There is another piece of code that had a TODO which was going in the same direction. So I also work on that one.

@egeerardyn: I was considering to use a handle to the source object. This would also allow to deal with normalized units. But note, that normalized units can have a different conversion factor for x and y direction. This could be solved by using as vector srcValue with two elements, x and y. Still, for the moment I just wrote a lightweight function. If more functionality is needed, we can extend convertUnits() for that.

@okomarov: I did not store the converted / original units, yet. I think at the moment, the source is coming from a get(..., 'Position'), and is converted towards something else. I do not see any forward - backward conversion that might gain from such storage.

At the end: I just started to use git / github (before I only used svn) and still try to establish a good workflow. So I'm not sure what is the best praxis when changing something in a pull request, that is still in discussion. I now created a new branch upon it and did the quick change in it.