bump version to 0.7-rc1

bump version to 0.6

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

default CC to gcc

posix c99 does not accept `-pedantic`

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

bump version to 0.5

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

allow specify DATADIR (to install desktop file)

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

bump version to 0.4

remove `--long` from git-describe command

Merge branch 'main' into wlroots-next

bump version to 0.4-rc3

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

bump version to 0.4-rc2

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

bump version to 0.4-rc1

Merge branch 'wlroots-next' into main

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

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)

add missing library (xcb-icccm)

this library is also used by wlroots, so nothing new