bump version to 0.6

prepare CHANGELOG.md for 0.6

Revert "place child clients above fullscreen clients"

This does not work as intended. Lets revert it temporarily and add it back
after the release.

This reverts commit 298949bbc4eae8cedb9cdd11cfc9ebd139ac5d5f.

Fix applybounds

Applybounds doesn't move client when it overlays
only with border with monitor to the right.

Apparently, c->geom.width already includes the border
as well.

feat: focus empty monitor when clicked

use round(3) and ceilf(3) from the math library

ΔSLOC: -1

set preferred scale after the first commit (XDGshell)

drop useless maplayersurfacenotify()

set O_NONBLOCK flag to stdout

add a note about having at least a dummy rule for `rules[]`

Closes: https://codeberg.org/dwl/dwl/issues/656

add bugref about why we call updatemons in outputmgrapplyortest

set preferred scale on creation (LayerShell)

correctly report position to xwayland clients

Previously we didn't take into account their borders requiring us to add
`borderpx` to override_redirect clients.

Fixes: https://codeberg.org/dwl/dwl/issues/651

add bugref for negative x,y monitor position and xwayland

Reapply gamma LUT when re-enabling an output using wlr-output-power-management

try to limit (79 characters) the line lenght in the Makefile

Updated power management handling to address issues raised in the PR

Prevent updatemons() from removing monitors that have been put to sleep from the layout

Implement support for output power management

This patch is based on the original stale patch by Guido Cella @guidocella.
It has been modified to apply cleanly to the latest v5.0 tag. Since the SLOC
limit is now lifted, this core feature should be merged into dwl upstream.

Thanks to Dima Krasner @dimkr for the cherry-pick.

Closes: #559, #525

default CC to gcc

posix c99 does not accept `-pedantic`

Fixes: https://codeberg.org/dwl/dwl/issues/584