Public Task landing page

[mvexel]

Currently there is no way to inspect a task if you're not logged in. This would be good to have to give people interested in seeing the lineage of a change in OSM a place to go. The public task page should have the following content:

• A brief explanation of what MapRoulette is
• A description of the challenge the Task is a part of
• The Task map (can be static)
• The Task instruction
• Timeline of actions + user(s) performing them (created, claimed, fixed)
• A read only view of the conversation belonging to the challenge
• Action: "Log in to comment"

[mvexel]

For the comments, this is the set of requirements we landed on:

• Will have a tab for discussions on Challenge browse page
• Threaded but only 1 level deep
• Read only when not signed in, sign in to comment
• Abillity to @mention other users
• Challenge creator
• More compact layout compared with Task comments
• Each comment has a relative timestamp (... hours ago, … days ago) and the username (clickable to go to MR user profile page) underneath
• Comment box fixed to bottom of layout
• Comment thread box scrolled to bottom (latest comment) by default
• Comments by Challenge author emphasized (yellow dot in front of username)
• Add option (checked by default) in user settings to get notified about any new comment to a Challenge you are the owner of
  • Need to consider an option to “mute” a Challenge thread to disincentivize user from disabling notifications altogether

[mvexel]

Once we have this, we should start adding this specific task URL to the changeset comment instead of the challenge URL. This would benefit from #225 to shorten the links.

[mvexel]

This may need some discussion for inclusion in 3.12 but I am adding it here as a "stretch goal"