- added support for key-based panning in 3D graphic engine. Moving the mouse wheel while pressing the CTRL key will pan up-down and while pressing SHIFT key will pan left-right
- solved issue #292 where a new geometry renamed with many underscores failed to store the name in a saved project
- the name for the saved projects are updated to the current time and not to the time of the app startup
- some PEP8 changes related to comments starting with only one '#' symbol