Add "pull --prune" option

[widogg]

Problem description Sublime merge has several pull and fetch options. However, it does not includes pull --prune (while it does include fetch --prune).

Personally, I end up having to run 2 commands while I could be running only one. This option is present in the git CLI

Preferred solution

Add the option to pull --prune to the Pull Options combo

Alternatives

Another alternative would be to accept arbitrary text as parameters