Add expert augmented diff and attic query controls

[nrotstan]

• Add new control for users in expert mode to each history entry in task
  history table for viewing an augmented diff between two entries or attic
  query data for a single entry

• Selecting two separate entries will show an augmented diff of the
  changes between those entries in Achavi in a new browser tab

• Selecting the same entry twice will perform an attic query and open
  the data in either JOSM (if the user has selected it as their editor) or
  Overpass Turbo in a new browser tab

• Add new atticQueryOffsetMinutes config setting for adjusting history
  entry timestamps for the purpose of querying attic data to ensure that
  data has had time to become available (defaults to 10 minutes)

• Reorganize some of the projectController bbox code into separate
  methods to facilitate easier reuse

[ethan-nelson]

• controls appear when expert mode activated, disappear when deactivated
• double clicking new box shows changes in overpass turbo
• double clicking with JOSM selected opens amazingly
• clicking different boxes opens augmented diff in achavi with time differential (e.g. when selecting a mark done and comment, they have the same time and so changes don't show up--while selecting two different marked done shows differences)
• old view osm changesets button still works
• old view in overpass turbo button still works, and verified each user shows up for node, way, and relation

[ethan-nelson]

Thanks @nrotstan !

@russdeffner do we have an advanced validator training curriculum--or is there a better place we could start collecting information on expert mode features? I think a wiki page in the TM GitHub repo is warranted to for non-HOT users.