py-rtree: Added package (#1548)

* py-rtree: Added package

* py-rtree = RTree (spatial indexing) data structure for Python
* libspatialindex = Underlying C library wrapped by py-rtree

* Flake8 and Copyright issues.

* Fix Python syntax error.

* Fixed dependency type error.

* Added new version, based on updates requested in upstream PR

* 1. Change cmake to build dependency.
2. Updated to CMakePackage