Nyall Dawson e6ec1ec53e [FEATURE][API] Add iterator for QgsGeometryCollection
Iterates over the geometries in the collection, allowing this type
of code:

  gc = QgsGeometryCollection()
  gc.fromWkt('GeometryCollection( Point(1 2), Point(11 12), LineString(33 34, 44 45))')
  for part in gc:
    print(part.asWkt())
2018-12-07 05:51:27 +10:00
..
2018-07-02 06:16:49 -05:00
2018-05-14 11:02:28 -04:00