Add support for data object deprecation mechanism without new-version upload

[mirzov]

There are at least two use cases for this:

1. Bad data that does not (and is not going to) have a new version.
2. Situations when a data object needs to be deprecated with not a single other object, but a combination of a few others. Case in point is the situation of OTC where L2 is cut not from the latest L1 (like ATC does, for example) but from older data. This makes it impossible to deprecate the latest L1 with the latest L2. Instead, the latest L1 (at the point of L2 creation) has to be deprecated with a combination of the newly created L2 and the new latest L1 (whose temporal coverage now starts where that of the new L2 ends).

One mechanism catering to these use cases would be adding a class of Deprecations, possibly with only the standard RDFS properties of label, comment and seeAlso, and a new property isDeprecatedBy on the data object (or reusing a similar one from en existing vocabulary, for example from PROV-O).