Added renderCollectionBefore and renderCollectionAfter events

Hi

This PR adds a new before/after events couple.

The renderCollection events are triggered once per renderPass which lets plugins handle more granular action than the generic renderBefore / renderAfter events :

renderBefore
renderCollectionBefore (pass 1)
renderCollectionAfter (pass 1)
renderCollectionBefore (pass 2)
renderCollectionAfter (pass2)
[pass 3, 4 ... if enabled]
renderAfter