[FR] Properly handle folder names with spaces in autocomplete results

[aph3rson]

Right now, if you're using tab completion to autocomplete a folder name with a space in it, the full name is included without quotes (e.g. cd Library/Private Documents rather than cd 'Library/Private Documents'). It would be nice if the completion functionality was able to detect paths with spaces in them, and surround them with quotes (or move quotes around if need be).