Capability to delete reponses becomes capability to delete or modify
responses.
This also resolves MDL-51659 (incorrect events answer_submitted and
answer_updated) by deprecating them and replacing with the answer_created
The problems was that blocks editing breaks if you redirect
after if (data_submitted()) - all form actions must make sure
it is really their form, otherwise they may hijack the post from
block actions.
Note that this is not a problem for mforms, only legacy forms
are affected.
# Conflicts:
# mod/choice/view.php
