flag deprecated schema.org types and properties

[newgene]

We currently load the schemaorg-all-https.jsonld, which includes

the definition of all terms in, all sections of, the vocabulary, plus terms retired from the vocabulary (See the attic section for details).

The retired item can be identified with schema:isPartOf has "https://attic.schema.org" in the value:

{
    "@id": "schema:variablesMeasured",
    "@type": "rdf:Property",
    "rdfs:comment": "Originally named [[variablesMeasured]], The [[variableMeasured]] property can indicate (repeated as necessary) the  variables that are measured in some dataset, either described as text or as pairs of identifier and description using PropertyValue.",
    "rdfs:label": "variablesMeasured",
    "schema:domainIncludes": {
        "@id": "schema:Dataset"
    },
    "schema:isPartOf": {
        "@id": "https://attic.schema.org"
    },
    "schema:rangeIncludes": [
        {
            "@id": "schema:PropertyValue"
        },
        {
            "@id": "schema:Text"
        }
    ]
},

We should label retired types/properties in the DDE's schema UI (schema viewer and class-extension).

[gtsueng]

Maybe the retired properties and types can be displayed as gray or red text (or with strike through) to give some visual indication that it has been deprecated. This way deprecated properties can still be viewed, but there are visual cues to indicate they shouldn't be used.