Allow users to choose moderators for topics

[FreeTrade]

I think competitive moderation will be a great addition and necessary for Member (and Memo) as the platform grows in users. I think we'd address this by adding some protocol actions to nominate a user as a moderator either for a specific topic, or site-wide. Members should also have an ability to rate actions as spam, and users as spammers, so that neither should appear when other Members are viewing a topic where that Member has been nominated as a moderator.

[FreeTrade]

Protocol Actions

Designate Moderator, 0x6dc1, address(20), topic(variable)
Dismiss Moderator, 0x6dc2, address(20), topic(variable)
Hide User, 0x6dc3, address(20), topic(variable)
Unhide User, 0x6dc4, address(20), topic(variable)
Hide Post, 0x6dc5, txid(32)
Unhide Post, 0x6dc6, txid(32)

Member Implementation

If a member(A) requests a list of posts for a topic, where member(B) has been nominated by member(A) as a moderator for that topic,
then any posts that have been hidden or posts by members that have been hidden by member(B), or by a member(C) that has been nominated
by member(B) as a moderator for that topic, will not be returned in the search results.

If no topic is indicated or is an empty string for the first 4 actions, hides will operate for all topics.

Expected usage

A moderation group is established as a new Member profile - named 'Politics Moderation Group' for topic 'politics'
'Politics Moderation Group' nominates members X, Y and Z as moderators for topic politics.

Member 'Bob' nominates member 'Politics Moderation Group' as a moderator for the topic 'politics'.

Members X, Y and Z mark some posts as hidden, and mark some users as hidden.

Member 'Bob' will not see any posts marked as hidden or posts from users marked as hidden when viewing the 'politics' topic.

note: edited from 5 to 6 actions to include 'dismiss mod'

[FreeTrade]

Basic support added.

Still need to add sitewide moderation, and tools to see moderator actions etc.

[FreeTrade]

Sitewide moderation is added. Also ordinary members can only nominate moderators if their handle ends with 'filter' or 'group' (case insensitive. members whose handles end in 'filter' or 'group' can nominate any other member as moderators. This enforces the expected usage as described above and simplifies the interface.

Still require more tools to view moderator history, and allow unhide actions