Precising licensing

The copyright before was MPL for createsvg.hxx and LGPLV3+ for anything else.
For the following commits, it's AGPLv3 only.

Signed-off-by: Lennard Wasserthal <Wasserthal@nefkom.net>
Correct use of the file menu

Signed-off-by: Lennard Wasserthal <Wasserthal@nefkom.net>