zgeo.wfs Rtree index
===========
Rtree index for Zope 2 ZCatalog (copied from Sean Gillies's zgeo.spatialindex, which works under Zope 3)

Usage:

  >>> from zgeo.wfs.geocatalog.index import BaseIndex 
  >>> index = BaseIndex()
  >>> index.rtree.add(1, (1.42, 2.54, 3.3, 2.89))
  >>> index.rtree.add(2, (4.4, 10.3, 5.9, 13.8))
  >>> index.rtree.intersection((0, 0, 3, 3))
  [1L]
  >>> index.rtree.intersection((0, 0, 20, 20))
  [1L, 2L]

