Optimize localized ui re-render

[petterik]

When lajt discovers changes in the ::pull op, make it easy to get the focused query for the data that has changed, such that one can map the focused query to the deepest component in the UI tree.

Example:

;; PeopleList query:
[{:people (om/get-query PersonItem)}]
;; PersonItem query:
[:person/primary-email]

If PeopleList has rendered some people and the :person/primary-email changes for any of those people, the ::pull op should recognize that [:person/primary-email] in query [{:people [:person/primary-email]}] belongs to a component of PersonItem, and it should be able to re-render the specific one that has changed (maybe by ident?).

[petterik]

Or this doesn't matter, as this is resolved really quickly by shouldComponentUpdate?

[petterik]

shouldComponentUpdate is not sufficient as parents will have their render triggered, even though only the component that cares about :person/primary-email in this case, should have to be re-rendered.