Semtools

When we remove an Observation...
-do we want to remove the Context it might be providing for another Observation?
-do we want to have a warning that forces you to remove the Context that uses that Observation before you can delete it?

When we remove a Measurement...
-I am deleting it from the Observation i is part of and also the attribute mapping it has

General note:
-I'm not sure when/if we should attempt to remove ontology references used in the Annotation. It seems like this should just happen when we finally serialize the Annotation instance (it would verify that all the ontologies being referenced are actually included in the NS defs of the annotation doc). This is an implementation detail, but I wanted to note it.

Grouped the options, hopefully it's clear what they do and what the implications are.

Decided to require the Context be removed before letting them remove the observation that was providing the context

If a user wants to remove an observation that is context for other observations, I think the system could prompt the user warning them that the observation serves as context, and whether they want to proceed. Alternatively, I think just removing the observation and the context is enough. It seems like having to remove all of the context rels before you remove an observation in some cases could be tedious.

The same goes in the other direction, i.e., if a user wants to remove an observation that is contextualized by other observations, the context relationships should also be removed.

Original Bugzilla ID was 4737