[OpenSCAD] bug: missing bracket pair causes assertion violation

[Britton Kerin]

This is probably known and just not done but thought I'd report anyway.

In openscad-2010.01, this code:

  polygon (points = [[0, 0], [100, 100], [100, 0], [0, 100]],
           paths = [0, 2, 1, 3]);

causes this assertion violation:

  ASSERT: "!isEmpty()" in file /usr/include/qt4/QtCore/qlist.h, line 246
  Aborted (core dumped)

Britton