Rationalisation in this PR applies the following logic to enumerations and their values:

• An Enumeration is defined as type rdfs:Class and rdfs:subClassOf of http://schema.org/Enumeration
• An enumeration value is not defined as type rdfs:Class but is defined as type a valid Enumeration

Also includes unit test to identify wrongly defined enumeration & enumeration values.

Snippet for Site Improvements section of releases.html:

<li id="2236"><a href="proxy.php?url=https://github.com/schemaorg/schemaorg/issues/2236">Issue #2236</a>:
(implemented in <a href="proxy.php?url=https://github.com/schemaorg/schemaorg/pull/2250">PR #2250</a>):
Rationalised definitions for enumeration values so they are consistent.  Added tests to confim consistency.
</li>

This has been reverted; discussion in the issue.

See also #2443