Add support for Groups

[jessdecker]

Abstract

Add the ability to create interest groups to allow for a more focussed community organized around group membership rather than just hashtags. Initial focus would be on public groups, and later add support for private groups with encrypted memberships and posts.

Implementation

Core changes:

• Add a GroupMembershipEntry type - Created to mark a User as a member of a Group
• Add a GroupEntry type - Contains a groupId, groupName, shortDescription, creatorId
• Add a property to PostEntry for groupId - not populated for regular feed posts. populated with a groupID to make it only appear in a particular group

Backend changes:

• Add api to query for a user's group membership
• Add api to query for posts for a groupId
• Modify reply post functionality so that replies carry forward the parent post groupId

Frontend changes:

• In the browse page, add another tab after Following/Hot/New to make it Following/Hot/New/Groups

Further considerations

There would need to be functionality to discover groups and invite users to groups

Alternative options

Make a group behave more like a User - with creator token functionality

Feedback welcome!