Smallfix: cat no longer chokes on empty args.
Attempt at dirname completion.

Works, but not the way we'd like it to.
Change flow of autocomplete.

Now guiterminal is responsible to separate the prefix and the fragment
to be completed. It's much nicer this way. Completer should later need
to get the prefix to make an educated decision.
Tweak autocomplete display behaviour.

No longer adds lines to textbox if there are no results.