This restores the ability of %reset to clear references to objects created in a %run-ed script. See bug #141 (not actually closed by this, but it gets us back to where we were when the bug was reported).
Looks great to me, and the behavior is as expected at least as far as successive interactive runs of tclass are concerned. Tests pass too, so merge away. Thanks!
Added a little tweak to test_tclass so that it would fail if all references were kept until %reset.
Rebased and merged to avoid merge handle.