API method to get unseen posts count

Hi @raspbeguy,

If you GET the /api/v3/teams/TEAM_ID/channels/members route or use the getMyChannelMembers of our Javascript/Go clients, you'll get back an array of ChannelMember objects for all of your channels on the given team. If you call it with an empty TEAM_ID, you'll get ChannelMembers for all of your DM channels.

Each ChannelMember contains a msg_count field (the number of unread posts) and a mention_count field (the number displayed in a circle next to the channel name in Mattermost). They also have a last_viewed_at time as well if you still need it.