Added GeoJSON MultiPolygon support.
Improved _list/bbox-filter.

This commit is a mess but here's what it does:
- Moved some var declarations inside the while-statement. This makes no real
  difference but it increases readability.
- Changed semantics from outside_bbox to inside_bbox because that allows me to
  initialize every function variable as the atomic pass() statement.
- inside_bbox then accepts the other bbox as argument 'bbox2'.
- The commented data-exhaustion statement was kind-of wrong (although never in
  use).
- I worked out a very crude comparison of similar geometries: it just checks if
  bounding boxes are close to one another. It still may suffice to merge almost
  duplicate geometries being attached to their documents.
  This is an inherent problem of ESRI shapefiles!! It was a poor design in 1998
  and it is poor today!!!
Moved some common functions into script/google.maps.js.

This library sucks: It does not load Google Maps API and neither Maps or LatLng
or LatLngBounds seems to be present. I would call it 'work in progress' but it
is way too useless for this coveted accolade!!!