Bug #1711112: Remember printer settings

This fixes bug #1711112: https://bugs.launchpad.net/inkscape/+bug/1711112

Now, when you apply changes in your print settings dialogue, it will remember those settings when you re-open it.

On Windows, there's still a problem where sometimes it doesn't remember the settings in your driver's preferences window, but that's a GTK bug, not an Inkscape bug.