absent some vs absent all

[sbello]

related to #332

There has been inconsistent usage of "absent" across and within phenotype ontologies. When we say "absent X" where X is something that in normally present in multiple copies do we mean some of X are absent or that all X are absent. For example does "absent teeth" mean absence of all teeth or absence of some teeth.

We have have extensive discussions on the UPheno calls (https://docs.google.com/document/d/1WrQanAMuccS-oaoAIb9yWQAd4Rvy3R3mU01v9wHbriM/edit?usp=sharing)

We eventually decided that absent should be used for absent all as we can use decreased number for absent some when we are referring to anatomical entities. We should add a note to the new absent terms to make sure this is clear to curators.

We should also add a similar note with a recommended patter to use for absent process but I'm not sure what the term to recommend for this is.

There is still the issue of reasoning over these terms as we do not want to have absent sub-type Xa to be a child of absent X (e.g. absent incisors should not be a child of absent teeth)