Allow using monospace font in text fields
It is currently not possible to define a font in Text fields but it is sometimes useful to be able to show text using fixed-width fonts for showing code or reStructured text, for example.
I propose to add an attribute "monospace" which by default would be false (0) but if set to "1" it uses a monospace font.
In both GTK and Sao using the font "monospace" will use the default monospace font of the system.
An alternative would be to allow setting the font with a "font" attribute. Not sure if that is really necessary.