Message functional improvements

[edwh]

• On Communities/Explore, use the visibility plugin to pick up new messages.
• In Message sendReply, when replying, if the group approves membership, then we will not actually be a member after auth/joinGroup. We might be rejected. Probably in that case we shouldn't be allowed to reply to this message, but we will. I think this is the same behaviour as in the old version, but that needs testing and consideration of how to handle.
• In MyMessage, there's a window we've seen in the past where the autorepost hasn't happened yet. Should say 'soon' if autorepost time is in the past.
• In MyMessage, when we click to expand, the visible text may be off the top or bottom of the screen. Need to make it visible.

[edwh]

Membership approval no longer supported.