Fix several issues, attemt to fix zooming issue

projects/common-map/src/fm-map/services/device-orientation.service.ts

@@ -40,7 +40,10 @@ export class DeviceOrientationService {
   getCurrentCompassHeading(): Observable<number> {
     return Observable.create((observer: Observer<number>) => {  
         window.addEventListener("deviceorientation", (event:DeviceOrientationEvent)=>{
-          observer.next(this.compassHeading(event.alpha,event.beta,event.gamma));
+          let heading = this.compassHeading(event.alpha,event.beta,event.gamma);
+          if(!Number.isNaN(heading)) {
+            observer.next(heading);
+          }
         } );
     });
   }