Move setting of font properties used throughout to themeInterface.
Add new settings "currentScale".
The properties are kept in main (subsurfaceTheme) in order not to do
a big search/replace.
Update settings to use currectScale and signal changes in themeinterface.
Signed-off-by: jan Iversen <jan@casacondor.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>