add GeoJSON import & export

[noerw]

I added functionality to import geojson data into the map. This enables the reuse of existing datasets in/from other applications.

To do so, a new sidebar panel "Tools" is introduced:

Also, some other improvements were made:

• improve propagation of mapview-changes to other users, by using leaflets event API instead of native browser events. now all map movements are registered
• fit the mapview to all features when loading a non-empty map
• fixed edgecases where multiple simultaneous $scope.$apply() calls were made, resulting in buggy UI
• fix corrupted API stream in development env, which was introduced by connect-livereload injection

[dwilhelm89]

Very nice changes. Thanks a lot!

However, there are two issues which should be fixed before merging.

Imported GeoJSON features do not seem to be synchronized between different clients. They only appear after another edit or after refreshing the page.

Apparently, there is still a little design issue left to fix (FF and Chrome).

[noerw]

oops. fixed in e4efb794ffa1c62510f0bac73cfafba44c9dc083 :)