CRS ontology and API

[karimbahgat]

One of the basic ideas of PyCRS is to provide a taxonomy/ontology of the underlying components of a CRS, which is independent of particular CRS format specifications. Ironically, this is based on the WKT 1.0 format specification, simply because it seems to provide a fairly direct mapping to the underlying mathematical concepts and components.

It seems some of the WKT v1 components, which grew out of the initial ESRI prj file spec, is not ideal in all cases. A new WKT v2 is now defined as an ISO standard, and have made some changes to the ontology that deals with some of the older issues.

This is just a note regarding what the PyCRS API is currently based on, and to say that the next major version of PyCRS should probably be based on WKT v2 instead.