get location from feature

[dbauszus-glx]

By default the highlight interaction will call the /location/get method which in turn calls the getInfoj method before the location is decorated.

A layer may be loaded from a file. In this case no database connection is required. All feature properties are available on the feature.

A featureLocation flag could be introduced for layers. The getInfoj method would then assign the infoj entry values from the feature properties and not sent a location_get query.

Location from feature properties must not be editable.