Need to be able to delete new lemmas

[Jefficus]

This is Phase 4 as described in bug #426937, in which we need to implement the ability to delete lemma assignment links and possibly also lemma documents, which implies both shallow and deep delete. We will conduct some discussion on these needs before proceeding to implement.

[Xiaonuo Gantan (xiaonuogantan)]

Quote Jeff:
"This is a relatively complex operation, in that we might need both shallow and deep deletion. (Are we deleting the link between the active word and its lemma, or are we deleting the lemma document itself, along with all the links to it from other words? As such, this will be handled under a seperate bug entry, as there will need to be discussion about expected behaviours, and those discussions should probably wait until we've had a chance to use and explore the new lemma system first."

I've finished phase 3. What's the plan for phase 4? I suggest both shallow and deep deletions should be added and the user can choose which way he wants when he deletes one. I would also recommend presenting references to the lemma and the active word in different documents to the user so he/she can have an overview of the impact of deletion before making any actions. For example, something like:
Lemma: verb
Active Word: work
Documents containing this lemma:
Doc #1 -- 3 sleep-verb, 4 eat-verb, ...
Doc #2 -- ...

[Yin Liu (yin-liu)]

Since, in the new system, lemmas are just one kind of annotation, we
should handle them in the same way we handle other annotations. Here is
how I see it. Right now, I can delete the active word or delete the
lemma annotation. We also have the option 'redo existing annotation'
which can effectively create a different relationship between the active
word and another annotation. So I think the current system works fine
and we probably don't need to add any new features to it, at least for now.

Yin