Rewire moving map functionality

[ri0t]

Backend

• Provision (?) Vesseldata as self
• Add coordinates to Vesseldata self via referenceframe
• Add Mapview for encountered Vessels Not yet, needs OSDM/AIS/... first

Frontend

• Fix Epic: MapView sharing support #43
• Mark/sort/visualize differently Vessel Mapviews, esp self
• Add button to follow self

[ri0t]

Actually i'd prefer to bind this to a mapview

[ri0t]

Almost done. Just need to make sure, the reference frame works and contains some coordinate. Maybe, we'll want this configurable - in case there's more than one coordinate sensor source.

[ri0t]

The details about marking a non-own vesselview etc. are a bit up to discussion, so i'll close this and we'll refine it later - the core mechanics do work :)