Provide a way to programatically obtain the library version

[hobu]

It may be necessary for applications to be able to do fine-grained things based on the version of libspatialindex that is currently linked. I propose that we use a GDAL/libLAS-style approach with an include called #Version.h (or other appropriate name).

 http://liblas.org/browser/trunk/include/liblas/capi/las_version.h

The only downside I see is remembering to increment things at release time.

I'm open to other approaches than this rather simple one, but I think it is important for developers to be able to determine at compile time what version of libspatialindex they might be dealing with.

Howard