Adding two properties for "process has first/last instant"

[giacomodecolle]

Solves #605

I would appreciate some guidance on how to mint IRIs, I wasn't able to find any in the repo. Similarly to see if this is following other CCO contribution guidelines that I might not be aware of.

Regarding the two properties, I would also like to change the definition to says something along the lines of "x exactly occupies_temporal_region z", that is, to say that the temporal extent of process x is exactly the temporal extent of temporal region z.

It also sounds reasonable to me that this relation should be functional.

[johnbeve]

@giacomodecolle Did you see the guidance here by chance: https://github.com/CommonCoreOntology/CommonCoreOntologies/blob/develop/documentation/contributing/registering%20IRIs.md

There is an IRI registry branch here: https://github.com/CommonCoreOntology/CommonCoreOntologies/tree/iri-registry-branch

I agree that shrink-wrapped occupation should be functional.

[giacomodecolle]

Updated the axioms and IRIs, do they go in a separate PR?