Refs #3089, hack into realtime map a bit to make it extensible enough for visitor profile use cases.

Notes:
  - Added realtimeWindow & removeOldVisits query parameters so amount of data displayed can be changed.
  - Added changeVisitAlpha query parameter so opacity does not have to be changed if desired.
  - More missing cleanup added for realtime map.
  - Only show map if there are visits that will display on it.
  - Removed some dead code from realtime map.