2 small fixes

Hi,

I've fixed the memory semantics in the display settings - the font refs should really get retained s.t. the display settings can make sure they have a valid fontRef.

Furthermore I've added support for specifying a default text color and fixed a crash by providing default display settings.

In case you wonder why I forked your repo instead of the original, I saw that you added quite a few nice things (especially the separated display settings) which I wanted to add myself. I don't know if you're in any way related to Uncodin, but do you plan on submitting a pull request to the original repo?

cheers Matthias