overlapping CodeList vs non-codelist properties

[VladimirAlexiev]

Related to #189

There are properties that seem to have the same meaning, but

• one is coded (object prop pointing to a codelist)
• the other is uncoded (data prop with range xsd:string, i.e. free text).

For example:

• https://vocabulary.uncefact.org/AccessRightsTypeCodeList shows unece:accessRightsTypeAccessRightsCode with descr "The code specifying the access rights, such as unlimited, restricted, prohibited, for this requesting party." and range unece:AccessRightsTypeCodeList
• the ontology (converted to turtle):

  uncefact:accessRightsCode
      rdf:type                        rdf:Property ;
      rdfs:comment                    "The code specifying the access rights, such as unlimited, restricted, prohibited, for this requesting party." ;
      schema:rangeIncludes            xsd:string ;

Furthermore, the prop names are inconsistent and the coded prop name is just baroque. Merge and unify to eg the following naming:

uncefact:accessRightsType
        rdf:type                        rdf:Property ;
        rdfs:comment                    "The code specifying the access rights, such as unlimited, restricted, prohibited, for this requesting party." ;
        schema:rangeIncludes            uncefact:AccessRightsType.

uncefact:AccessRightsType a rdfs:Class;
  rdfs:comment "A character string used to represent the type of access rights.".