add support for the ext-idle-notify-v1 protocol

for now we use macros to support both KDE idle and ext-idle, wlroots will
likely drop support for KDE idle in 0.17

wlroots check map state of layersurfaces this for us

Merge remote-tracking branch 'djpohly/main' into wlroots-next

properly handle cursor motion when button is held

Based on: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3653

avoid setting duplicate cursor image

Reference: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3436
Based on: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3595

destroy renderer and allocator in cleanup()

fix bad condition

fix various segfaults when selmon is NULL

change cursor surface in internal calls of motionnotify()

and call motionnotify() after unmapping a client
and when focusing a client

Fixes: https://github.com/djpohly/dwl/issues/308

remove unused variables

rework Makefile

- allow user to use a different pkg-config binary
- restore almost all (and add other ones) warning flags (-Werror is not set)
- $(XWAYLAND) is added to our CPPFLAGS
- remove useless comments
- don't generate idle-protocol.h (not used)

make more permissive exclusive focus

now you can call focusstack() while a layer surface is focused and when it gets
unmapped the newly focused clients will be actually focused

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

add missing library (xcb-icccm)

this library is also used by wlroots, so nothing new

change the default term to `foot`

it is closer to the suckless philosophy (foot implements things that the suckless
guys would say that should be done by tmux or something else, but I have no
desire to create a new terminal emulator, and the best fit is foot)

also alacritty uses +100Mb of memory, more that dwl itself (~90Mb)
and foot only ~20Mb

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