Fullscreen 1 should respect no_gaps_when_only

[micamoan]

trafficstars

If you have dwindle.no_gaps_when_only=1, then set a window to fullscreen with fullscreen 1 (to keep the panel), you get gaps between the monitor edge and the window. It'd be nice if the config value was respected in this case and there were no gaps. (Perhaps an additional variable for whether fullscreen 1 should have no gaps?)