Add radiuschanging and centerchanging events

Author: eddydg

lib/main.js

@@ -154,6 +154,7 @@ class MapboxCircle {
             this._currentCenterLngLat[0] = newCenter[0];
             this._currentCenterLngLat[1] = newCenter[1];
         }
+        this._eventEmitter.emit('centerchanging', this);
         this._updateCircle();
         this._animate();
     }
@@ -170,6 +171,7 @@ class MapboxCircle {
         } else {
             this._currentRadius = Math.min(Math.max(this.options.minRadius, newRadius), this.options.maxRadius);
         }
+        this._eventEmitter.emit('radiuschanging', this);
         this._updateCircle();
         this._animate();
     }