Enable WKT/WKB Reader/Writer GEOS API (#63)

- New classes in geos.py, with persistent objects in geos.lgeos
- Use __del__() methods for classes that need to be cleaned up
- Move atexit register to a decorator at the bottom
- Writers implement get/set properties, where appropriate
- Use a different defaults for WKT Writer for GEOS 3.3.0 and up, to
  output 3 dimensions and trim extra decimals
- Set WKB Writer to have default output dimensions of 3 (#64)
- Deprecate older To/From WKT/WKB functions in geometry.base, particularly:
  - geom_from_wkt(data)
  - geom_to_wkt(ob)
  - geom_from_wkb(data)
  - geom_to_wkb(ob)
  - to_wkb(self)
  - to_wkt(self)
 - Keeping deserialize_wkb(data) for now, since I can't figure out how
   to avoid circular imports using the reader; only used for 'EMPTY'
 - Geometry objects now have a 'wkb_hex' property, for convenience
 - Test suites run using older WKT formatting, so these don't need to
   be modified; all tests appear to pass