Updated the basic CRUD features to treat discussion replies as entities.
Added an upgrade feature that migrates discussion replies from annotations to entities.
Ajaxified the discussion reply edit form.
Added notifications about replies to discussion topics.
Refs #5985 - Corrects admin message link to upgrade page.
Fixes #6211 - Corrects container write permissions bug
Missing translation
Registers entity class ElggDiscussionReply for subtype 'discussion_reply'
Corrected subtype control for discussion replies and added fallback for reply edit if link opened in new window
Refs #3693 - Updates container last_action on ElggComment::save()
Adds object:discussion_reply subtype registration on activate/deactivate
Merge pull request #6212 from Srokap/pr/6177

Migrates group discussion replies to entities