_mpc breaks when folder contains spaces

[Oliver Schmidhauser <oli@glow.li>]

Hi all!

I have a problem with mpc and the completion function.

mpc add Electronic/Las<tab>
mpc add Electronic/Laserkraft\ 3D/<tab>
mpc add Electronic/Laserkraft\ 3D/mpd error: No such directory

It seems to have a problem with the `\ ` in the path. It seems to be passed along to `mpc tab`, which it probably shouldn't.
I made a short video which demonstrates this problem: https://asciinema.org/a/vkNebrU6v5b9XYrMrdVeKpfB8

I've already raised this issue with mpc here: https://github.com/MusicPlayerDaemon/mpc/issues/7. The Maintainer of mpc made it very clear that the fault doesn't lie with mpc, but with zsh.

I've attached a .patch for _mpc which fixes this issue, as in it replaced `\ ` with ` ` before it is being passed to `mpc tab`. This probably doesn't fix the root of the issue, why `$word[CURRENT]` contains "Electronic/Laserkraft\ 3D" instead of "Electronic/Laserkraft 3D". It probably also breaks when a folder actually contains `\ `.

The second issue I have is `mpc tab` outputing errors while I am trying to autocomplete, breaking the current prompt so that I have to `Ctrl+C` and restart.

I've tested this with the minimal default config that generates when you run `zsh-newuser-install` and enable completion. I am running mpc 0.28 and zsh 5.4.1.

Thanks for any help,
glow