Several changes to make an Ubuntu 10.04 (lucid) with standard packages work:
 - Reconfigure polygonize.txt into test_polygonize.py to skip old GEOS
 - Remove advanced 'POINT Z EMPTY' WKT read, which raises ReadingError on
   older versions of GEOS (not sure which)
 - Remove 'six' development requirement, which isn't used anywhere
 - Several changes to setup.py:
   - Improve unittest2 requirement message
   - Force in-place build for 'test' for testing speedups