Code format, copyright headers and comments

During the code review I performed some small tasks on every file (but not for tests):

- Code formating 
- Add copyright headers to every file
- Added some comments
- Remove unnecessary constructors and fixed some minor code glitches
Not easy to reproduce, but I manage to do it with the following.

I used Thomas's RDF dataset from metadata-usecases/data/metadata_rdf.owl

Open the project. In the tree open Trials. Open one of the Trials. Select one of the signals. 

Then try to open AnalogSignal objects in the tree root.

Should trigger stack overflow in event dispatching.