fix compile error mixed declaration

Merge pull request #2 from guidocella/handleUnplug

Move sgeom assignment

Move sgeom assignment

There is no need to repeat this. This needs to be reculalculated in my
output-management implementation too, and since I'm already calling
updatemons, this patch avoids having to repeat the assignment again.

Keep client tags on unplug

When unplugging a monitor, each client is moved to the same tag number
as before on the new monitor

Handle monitor unplug

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.

Restore floating win position after mon add

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.

extract function and comment it

remove braces

fix multi monitors even more

When a monitor is created or removed, the geometries of the old ones
must be updated. This is also more efficient than before since we
calculate the monitor geometries only when creating and destroying
monitors. arrangelayers() is needed to recalculate m->w. arrange() is so
clients don't move to the left monitor when plugging or unplugging
monitors (clients keep the same coordinates but the field below them
changes).

simplify

fix multi monitors further

Fix layer surfaces without an exculsive area by using the right x and y
for the current monitor (by Stivvo).

remove unneeded line

The bug was caused by usable_area's x and y not being set in
arrangelayers. For example if on a 2nd HD monitor, x should be 1920
while the first one ends at 1919. So I don't see why m->m should be
recalculated after creating the monitor.

try to fix again

Calculate x and y of usable_area, not just width and heigth.

fix multi monitors

If you don't recalculate the monitor's geometry before arranging,
clients get arranged in the first monitor. I don't understand why this
fixes the bug since tile() uses m->w rather than m->m, nor why it needs
to be recalculated after creating the monitor but sway does it too.

Although not necessary to fix the bug I also made arrangelayer() do like
sway again and recalculate usable_area instead of reusing m->m, since
m->m seems to be incorrect until it gets recalculated shortly after in
arrange(), so I suspect that leaving usable_area = m->m will cause
issues under certain circumstances.

Someone with a multi-monitor setup or better knowledge of Wayland may be
able to figure out the cause of the bug. For now, this makes layer shell
work.

remove variable

use size_t for lengths

rename variable and merge 2 lines

simplify

use unsigned int for loop indexes

Don't let overlays lose focus

if you open a new window while an overlay is mapped, the overlay should
stay focused