font directory in preferenzes

Add an option to select/choose an different font directory in "preferences"

For designers it makes sense to have a freely selectable font folder, because we working with free fonts, as well as with commercial fonts, and also with maybe special fonts. It makes no sense to install hundreds of fonts in the system (OS) font-directory. It is much more professional to organize them in different folders. Tools like blender and gimp give us the possibility to change the font-directory, so please add this feature in Inkscape, so we can work in a professional and consistent way.

THX, Pinus