This allows to fix output-management: move clients to the monitor on the
left of the disabled one, instead of the leftmost (which might happen to
be the disabled one)
Also using wl_list_foreach() and then brake after the first iteration is
ugly and inefficient
Floating widndows with "x < removed monitor's width" aren't resized
(they used to disappear in negative coordinates).
Actually delete monitors when they are unplugged, recalculate sgeom and
give a new monitor to clients that were on the removed one with setmon()
arrangefloat() funcion has been exploded to save iterations in
cleanupmon().
Also if a monitor that supports auto suspension is turned off, dwl will
count it as unplugged (it will become unreachable and all clients will
be moved to the leftmost monitor). However, if at least one monitor
isn't plugged in, dwl will still crash the same as before.
Unlike sway, when the output configuration is changed and restored,
(unplug + plug the same monitor for example) previous application
positions aren't kept. This is due to the fact that on sway every
workspace is unique among all monitors.
Compensate the coordinate changes when adding a new monitor.
Every test so far confirms that monitors are always added to the left,
on top of the list, so every floating window's x coordinate has to be
incremented by the width of the new monitor.
Stivvo