Feature Request: Automatically update GPS data related to divesite

[Jan Schubert]

Nice to see GPS data added automatically if one picks an existing
divesite in the dive notes which already has GPS data defined before.
Would be even nicer if all dives gets updated when a GPS location to an
existing divesite is added later on. Would make life much easier for
people having hundreds of dives wanting to use this new cool feature.

//Jan