Done with 4a084c0df8. The reasoning was
that it was "confusing", but without using -add it is impossible to
append multiple items to a list in a single command and just overall
makes this less powerful. The code works fine. You might find yourself
in escaping hell, but that's on the user to deal with.
Also it's worth noting that -remove with object settings lists can
actually remove multiple items and unlike the other list option types.