Remove non-working shortcut editor

[ferdnyc]

AKA "FIx(ing) this shit".

It would probably be better if the shortcuts panel included a note about the lack of an editor, and maybe a pointer to a wiki page documenting how keybindings can be manually configured using dconf / gsettings, for the time being.

This PR does not currently contain any of that. It simply rips out the non-working component. Someone would have to write any additions to the ui/wiki.

Potential enhancements

• Add page to the wiki documenting manual keybindings configuration
• Add message+link in shortcuts UI, pointing to the manual-config information
• (For the sake of completeness:) A working keybindings editor

FIxes #1796

[ferdnyc]

@andyholmes @daniellandau

(I totally forgot about the shortcut editor, in my rundown of horribly broken components, but yeah it's been b0rked hard for a good long while now. Too long to leave it in there, as #1796 politely reminded us.)

[andyholmes]

Unless I'm mistaken, the only thing wrong with the dialog is that the hack it used to check keybinding availability no longer works.

If not having that is reason to drop the dialog, I'd suggest dropping keybinding support entirely, since manually entering shortcuts into GSettings won't really solve anything.

[ferdnyc]

Unless I'm mistaken, the only thing wrong with the dialog is that the hack it used to check keybinding availability no longer works.

Ohh, I thought it was only the dialog's availability detection that was broken, and causing it to refuse to save new ones. Sounds like it's worse than that.

If not having that is reason to drop the dialog, I'd suggest dropping keybinding support entirely, since manually entering shortcuts into GSettings won't really solve anything.

Well, the reason to drop the dialog is that it doesn't work. No matter what you press, it reports that the shortcut is already in use, and refuses to save it.

If manually defining shortcuts in the preferences wouldn't be any more effective, then I agree, we should just drop the whole feature. It's certainly frustrating to users, that we provide a UI which appears to let them do something, but Lucy-holding-the-football-style yanks it away from them at the last minute.

[ferdnyc]

(The code can always be resurrected from the repo, if someone decides to fix it. But at this point, leaving it there broken is worse than removing it.)