custom Styleable properties CSS prefix

[Tom Eugelink]

I've created my first control with custom CSS Styleable properties. Ignoring 
the fact that com.sun classes are involved, it worked pretty easily. Jim 
suggested that I also post the question about the CSS prefix I asked on the 
JFXtras mail list here is well. So:

I would like to suggest is to use the "-fxx" prefix for JFXtras CSS properties, 
so:
    -fxx-arrow-direction:VERTICAL;
    -fxx-arrow-position:LEADING;

If there is a good reason not to use "-fxx" I'd love to hear it.

Tom