Add tag categories

[MGlauer]

We need categories for tags. It would be best to link them to the classes in the OpenEnergyOntology.

[klarareder]

How can I link a tag to a class in the ontology? E.g. the Ontology already includes 'GeographicRegion'

[Ludee]

I added a column "category" to the "public.tags" table, which stores the colors. It is not used yet. I think the linking to the OEO is a better way.

[han-f]

Is there anything in parallel to the OEO development to add categories to tags at this stage?

[Ludee]

Link to the OEO: OpenEnergyPlatform/ontology#33

[jh-RLI]

It is easy to extend this and show categories in the dropdown.

Some thoughts on how to proceed:
First we need to decide what category names there should be and if the user can create them. We could also enable an input field to search for oeo terms (like in OEMetaBuilder) if we want to allow the user to link a tag to the oeo. Tags are also created automatically from the metadata, we need to decide which category to assign them to.

If we make this clear, I can define the next steps.