Fixed bug 2941 (or worked around it).  Also cleaned up the output somewhat.

Fixed (or worked around) bug 2941 by adding "limits => [.1, 1]"
  (The bug was:  with random seed 3544, it rejected the correct answer -20*e^(-t)*(-ln(1+t^2)/2+t*arctan(t))
Cleaned up the output somewhat, by using nicestring().