quitfullscreen() was replicating the functionalities of setfullscreen(c,
0)
Reusing setfullscreen() in quitfullscreen() leads to a 3 line function,
which is useless since quitfullscreen() is used once anyway
This fixes the bug that happens when changing workspace (or any time
arrange() is called) where there are fullscreen windows, which are still
fullscreen but leave the space for layer surfaces like waybar (which
should be hidden when going fullscreen)
Also as soon one fullscreen window is found hte function returns to
improve efficiency
Store position and size of windows before going fullscreen. This is more
efficient than arrange() and also works with floating windows
All the clients keep their original position because arrange() isn't
used after quitting fullscreen
Stivvo