optimize fish_completer path lookups

[scarlet-storm]

Check if string needs escaping before doing a path lookup. This avoids looking up the path, unless the completion contains special characters that need escaping

[fdncred]

Thanks. I'd like the $v to be a bit more verbose in name and also, it would be good to explain what's going on in the section below that describes what's happening. The cookbook needs to be able to explain itself.

[scarlet-storm]

Thanks. I'd like the $v to be a bit more verbose in name and also, it would be good to explain what's going on in the section below that describes what's happening. The cookbook needs to be able to explain itself.

I modified the section to add a short exlanation on the changes. Also renamed the closure variable to $row and the completion value variable to $value

[fdncred]

Thanks