mapnik/mapnik — pull request #2490 by hollinger (2014-10-03 18:49:07+00:00)
Title: Use margin attribute in group symbolizer

Update collision in group_symbolizer_helper to use the margin attribute instead of minimum-distance. Because group symbolizer is new to 3.x, I did not add any backward compatibility with minimum-distance attribute. Also added simple test case to test margin for group symbolizer.