Issue 106

[danirus]

The goal is to have a new field in each comment to keep the number of responses it has received.

• XtdComment method _calculate_thread_data updates nested_count values for all the comments related with the new incoming comment.
• When a comment is removed from the tree, the function publish_or_unpublish_nested_comments updates nested_count in parent comments, so that it only represents those comments that have is_public = True.
• A new command initialize_nested_count updates the nested_count field in the DB. The command is idempotent.
• Two new migrations added.
  • Migration 0007 adds the new nested_count field.
  • Migration 0008 populates values in the nested_count field.