Namespace convertion

[Sveino]

In general should KGraphPy not do any namespace conversion, but as we are moving from old namespace that changes for each version and could not support resolvable URI to a new version handling and resolvable namespace we need to be backwards compatible.

The following namespaces are the default:
(the next version of Network Code Related Canonical Extensions 2.4.0 will include this information)

<rdf:RDF 
        xmlns:cim="https://cim.ucaiug.io/ns#"
	xmlns:dcat="http://www.w3.org/ns/dcat#"
	xmlns:dcatcim="https://cim4.eu/ns/dcatcim# 
	xmlns:dcterms="http://purl.org/dc/terms/" 
	xmlns:eu="https://cim.ucaiug.io/ns/eu#
	xmlns:eumd="https://cim4.eu/ns/Metadata-European#"
	xmlns:nc="https://cim4.eu/ns/nc#
	xmlns:prov="http://www.w3.org/ns/prov#"
	xmlns:adms="http://www.w3.org/ns/adms#"
	xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>

The same exception instances are valid for this feature as #7

The relevant namespace for the CGMES exception are:

<rdf:RDF  xmlns:cim="http://iec.ch/TC57/CIM100#" 
		xmlns:eu="http://iec.ch/TC57/CIM100-EuropeanExtension/1/0#" 
		xmlns:md="http://iec.ch/TC57/61970-552/ModelDescription/1#" 
		xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	>

Conversion from CIMXML to TriG:
Convertion rule namespace :

CIM100	Persistent	Note
"https://cim.ucaiug.io/ns#"	"http://iec.ch/TC57/CIM100#"
"https://cim.ucaiug.io/ns/eu#"	"http://iec.ch/TC57/CIM100-EuropeanExtension/1/0#"
"https://cim4.eu/ns/Metadata-European#"	"http://iec.ch/TC57/61970-552/ModelDescription/1#"

Needs to update the spec for DifferenceModel and SchemaOps