add "all" to "set_desktop_for_window"

[acheronfail]

Fixes #39

I haven't tested KDE5 yet, unsure if the window.onAllDesktops property exists there. I'll check and report back.

[jinliu]

I think instead of another command, we can just change "set_desktop_for_window" to accept "all" as the argument. (Since it already accepts "current_desktop", it's trivial to modify the parser for "all".)

In the window menu, "All desktop" is a radio button along with other desktop radio buttons, thus it should be a special desktop number argument to align with the UI.

I'm considering dropping KDE5 support, so we can focus on KDE6 in this PR.

[acheronfail]

I think instead of another command, we can just change "set_desktop_for_window" to accept "all" as the argument. (Since it already accepts "current_desktop", it's trivial to modify the parser for "all".)

Makes sense - I've done that now 👍

I'm considering dropping KDE5 support, so we can focus on KDE6 in this PR.

Well that makes it easier for me! I just made it output an error if it's used in KDE5.