merge changes from simplegeo/geonode branch

[kashif]

https://github.com/simplegeo/geonode has some changes which might be useful to merge in here?

[booo]

@Kashif do you have any features in mind? Would be nice if we could create a list of missing features and features we can steal from the simplegeo branch ;)

[kashif]

Ok so looking at it I see there is only:

• add TopologyPreserveSimplify
• support older versions of GEOS without GEOSFree

[booo]

Adding GEOSFree does not make sense to me as we are using the c++ interface. Right?

I'm going to add two simplification methods/classes:

• http://geos.refractions.net/ro/doxygen_docs/html/classgeos_1_1simplify_1_1DouglasPeuckerSimplifier.html
• http://geos.refractions.net/ro/doxygen_docs/html/classgeos_1_1simplify_1_1TopologyPreservingSimplifier.html

I'm going to add a static simplify and topologyPreserveSimplify to the geometry object.

Maybe we should add isRing and hasZ as well?

https://github.com/simplegeo/geonode/blob/master/_geonode.cc#L105