Issue #996922 by dereine: Allow to directly access comment.nid, comment.uid without a relationship for filters/arguments/fields

Conflicts:

	modules/comment.views.inc

#366886 by Scott Reynolds: For "last comment time" if "count zero is empty" is set, use empty text for nodes with no comments.

#629984 by dagmar: Ensure that row styles are relationship safe and add fields they need to the query, such as nids and cids.

#539498: "Comments: Node link" did not work at all. Replaced with "Node: Add comment link" which is what that was supposed to do.

#400914 by joachim: Add a link field to get to comments for a node that works just like the normal links.

#375342 by dww: node_comment_statistics should be INNER joined because there is always 1:1 reference.

#353002 by neclimdul: Provide a filter for user posted or commented on to complement the argument with the same functionality.

#365283: views_handler_filter_ncs_last_updated improperly registered causing fatal errors trying to use it.

#321589: Add comment node row  template suggestions just like te node row variant, since it's already documented that way.

Since it's not easily possible to do the views filter block externally, bring the functionality directly into Views, including modifying the ajax for that to work.

Major re-organization of handlers. PLEASE NOTE: This drastically affected the Views module API and until modules are updated to match, they will stop working. Efforts have been made to ensure that this won't cause your site to crash, but that's partly up to the individual module as well.

Some refactoring of how handlers are handled, particularly with their default options. This is an unfortunately widespread change and will affect modules utilizing the API.

Comment links were not working; Lack of RSS row style was not properly validating; added node and user relationships for comment