now really fix clients not being focused after unmapping a layer surface

fix clients not being focused after destroy a layer surface

Revert "remove useless check of `m` in arrangelayers()"

This partially reverts commit d14ee99661e420c8e3d8fcc6791429a0e08bd915.

Checking if the output is enabled is necessary to avoid a segfault later

remove useless check of `m` in arrangelayers()

it is supossed to avoid a crash when we pass m=NULL as argument
however it would crash anyway and also because we should not pass m=NULL

fix use of loop initial declaration

forbidden by the suckless style

fix unmanaged clients not being unlinked from the commit listener

fix segfault when unlocking swaylock on two monitor setup

wlr_*_surface_from_wlr_surface() can return NULL if the surface
is being destroyed

Fixes: https://github.com/djpohly/dwl/issues/305

don't try to move outputs when its x,y hasn't change

when using wlr_output_layout_move() wlroots internally
change the state of the output to manually configured and
when updating the layout these outputs aren't ignored by
wlroots, leaving us at our own

prior run the startup command start the backend

this allow use clients like wlr-randr in the startup command

make sure the parent is mapped prior set monitor and tags

use wl_container_of() instead of data in some functions

add some comments

inline input_device in virtualkeyboard()

fix idle inhibitor check

previously we tried to get a client from the surface and then compare it with
the excluded surface, if we cannot get a client from the surface (e.g: a layer
surface) it just ignored all the next idle inhibitors no matter what

What I have should done is just checking if the excluded surface is equal to
the current idle inhibitor's surface and continue in case it is.

fix exclusive zone of unmapped layer surfaces

Fixes: https://github.com/djpohly/dwl/issues/302

resize the fullscreen background when resize the client

define _POSIX_C_SOURCE through CPPFLAGS

like dwm

fix condition that always evaluate to false in commitlayersurfacenotify()

remove obsolete check of c->mon in fullscreennotify()

since 19a8a095ebe782065903b9a03670560371302206 it's checked in setfullscreen()

set `c->prev` in setmon() and not in mapnotify()