[path-bar] Animate switching 'editable' property
[path-bar] Animate switching 'editable' property

Fade in/out the entry when switching the editable property. Unlikely
that you'd want to change this while the bar is visible I think, but
just in case.

pwithnall/mx,clutter-project/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx