Display class fields as a tree view from a tree model
requested to merge mortimerpavlitski/codevis:bugfix/mortimer/single_selection_list_not_apearing into master
- fixed oldSelection being accidentally modified by .subtract() in GraphicsView::mouseMoveEvent
- swapped field table to be a tree for view and model. this resulted in renaming the files.
- added database request for class field names.
- populated field model from database.
- fixed copy errors in comment headers
Signed-off-by: Mortimer Pavlitski mortimer.pavlitski@codethink.co.uk