Centralised comment management for space administrators

It would help space administrators to have a central location for managing all the comments in a space. This could be a new tab under "Browse Space", as suggested in CONF-5704. Or it could be some other mechanism.

The page would include comments on pages and on blog posts.

The space administrator would want to:

• See a summary of each comment. (Author, first line.)
• Expand a comment inline.
• Remove a comment.
• Respond to a comment inline.
• Mark a number of comments, then remove them all at once.
• Sort comments by date. Default sort order is by date, with the most recent at the top.
• Maybe sort comments by author.
• Maybe sort comments by page.

As an example, see the comment management page in WordPress. Screenshot attached.

Note:
A number of the points above are covered by related feature requests. We will use this issue to track the general request of grouping the comment admin in one screen. (For example, Space Admin > Manage Comments.)