Minor cleanup
Initial hierarchy processing
Handy world-pixel transformations
Slow but accurate bottom finding
Keep isolated depressions above
Multiple bottom finding strategies
Reorganize bottom finding implementations
Cleanup _find_poly
Polygon processing rewrite
Merge branch 'feat/hierarchy'
Profiling
Use 3D OGR geometries and introduce rtree idex
Use spatial index to subset points when considering polygon
Use rtree index in contamination check
Remove temporary dict key check
An attempt to store OGR Geometry within rtree

Lots of messages like below in console
ERROR 1: Empty geometries cannot be constructed
Return pts_dict back
Replace sort with min
Use bounding box from rtree otherwise fails to delete
Remove obsolete max stage & area constraints