Border blur / Border effects

[maltherd]

Description:
It would be nice to add an option for effects to borders. I was thinking of blur especially - shadow might not make sense in this context. This happened by default when setting blur with my old i3+compton config, and I liked it. Another idea is to add this behaviour directly to the existing options, if you find it acceptable.

See above, the blur effect is visible behind the transparent-black terminal window, but not behind the transparent-gold terminal title bar. Since the title bar has < 1.0 alpha, seeing the background so clearly behind it impedes the title's legibility. (Now, the color scheme is also at fault here but still ^^").