Allows double click with the middle mouse button to reply and fixed the
theming.

fixes #1462

See also:
https://daniel.haxx.se/blog/2023/01/08/copyright-without-years/
https://hynek.me/til/copyright-years/

This reverts commit 0035c359.

* Add member list and settings buttons to spaces

* Un-buttonify the member list button

* Properly button settings *and* members

This makes them less annoying when scrolling or accessing the popup
menu.

See also #860

Also fix a lot of warnings.

fixes #541

fixes #617

fixes #507

This reverts commit 74e32dd9.

This fixes some weirdness on some platforms, where Qt.openUrlExternally
does weird stuff.