Extend unit of measure symbol predicates to things other than units of measure

[rjyounes]

Currently we have three symbol-related datatype properties with domain UnitOfMeasure:

unitSymbol
unitSymbolHtml # as of 10.0.0
unitSymbolUnicode

The proposal is to extend the predicates to apply to anything, since things other than units of measure may have symbols, such as chemical compounds (this could have been relevant to one of my past clients). Thus:

symbol
symbolHtml
symbolUnicode

and modify skos:definition accordingly. We can include domainIncludes gist:UnitOfMeasure to indicate that one usage pertains to units of measure.

[uscholdm]

@rjyounes This makes sense to me.

[rjyounes]

DECISION: Add three predicates, deprecate existing ones

[uscholdm]

DECISION: Add three predicates, deprecate existing ones

If we decided to do this, why did we just create #992
See also #959, #579

[rjyounes]

I see the confusion. #992 should be entitled "Deprecate gist:symbolHtml and gist:symbolUnicode once the names have been changed." I'll clarify that. I agree it seems weird on the face of it to have one issue to rename predicates and another to delete them, but it actually makes sense in this context.