Remove Temperature Scale Singleton Classes

[jmkeil]

Currently, there exist in OM several subclasses of scale that are defined as oneOf a single scale instance (singleton classes). Further, there exists the class Temperature_scale, which is defined as oneOf some temperature scale instances and thous IRI doesn't fit to the naming convention. I don't see the need for the singleton classes (class definitions could simply use 'has unit' value <the scale instance> instead) and the oneOf definitions violate some OWL profiles (#79).

I propose to remove

• Celsius temperature scale,
• Fahrenheit temperature scale,
• Rankine temperature scale,
• Réaumur temperature scale,
• Temperature_scale, and
• the oneOf definition of thermodynamic temperature scale

and to state for all scale instances rdf:type om:ThermodynamicTemperatureScale.

[jmkeil]

There are a lot more issues regarding scales and temperatures:

• wrong (according to Weather-example.md) domain of om:hasScale
• wrong (according to Weather-example.md) restrictions of the om:Temperature and its subclasses regarding the use of om:hasUnit and om:hasScale (including #13)
• missing quantity om:KelvinTemperature