More voice and tense fixes.
Some languages put a space before a colon.
Revert 854286e.  Turns out not necessary.
Properly report a container as empty when it contains concealed or scenery objects.
Previously if an open container had only concealed or scenery objects, it would be
described as "box" rather than "box (which is empty)".
Commit baf8353 was partially wrong.  actor_act() DID sometimes return true.