Add clarity to use of verb metadata

We had a little debate here yesterday about verb metadata. This PR represents my personal view on what's implied as the way verb metadata can and must be handled. I see this as just clarifications, rather than new requirements, but I think that's open to debate.

Let's discuss!
A report displaying verbs should have the option to use either the verb display in the statement or it's own display for that verb from whatever source (see line 2191 above). If the LRS overwrites the verb, that removes that choice from the reporting tool. 

Format explicitly only applies to agents, groups and activities. Should it be extended to apply to verbs too? What about language maps in extensions and attachments? I think that'd be a separate issue and PR if so.