legend()'s numpoints parameter does not allow the value zero #176

Original report at SourceForge, opened Thu Nov 18 19:48:21 2010

The numpoints parameter does not allow the value of zero. I think it should be possible to have a legend with no point markers, but even if you disagree, there is still a bug.

Lines 251-252 in legend.py are:
if self.numpoints <= 0:
raise ValueError("numpoints must be >= 0; it was %d"% numpoints)

Either the code needs to be fixed to allow the value of zero or the error message needs to be fixed to say ">= 1"