unsplit at top level should no delete workspace

[Ted Zlatanov]

I have this in my configuration for WIonsWS bindings:

kpress("Shift+Pause", "WIonWS.unsplit_at(_, _sub)"),

2 questions:

1) why does unsplit on an empty WIonWS delete the WS?  That seems
   wrong.

2) how do I delete a workspace?  e.g. _ in a Lua query doesn't have a
   method I can use.

Ted