[osx] Remove All Pins command

Also fixed an issue where removing a selected annotation failed to deselect it.

platform/osx/app/AppDelegate.m

@@ -279,6 +279,10 @@ static NSString * const MGLDroppedPinAnnotationImageIdentifier = @"dropped";
     }
 }
 
+- (IBAction)removeAllPins:(id)sender {
+    [self.mapView removeAnnotations:self.mapView.annotations];
+}
+
 #pragma mark Help methods
 
 - (IBAction)showShortcuts:(id)sender {
@@ -438,6 +442,9 @@ static NSString * const MGLDroppedPinAnnotationImageIdentifier = @"dropped";
     if (menuItem.action == @selector(dropManyPins:)) {
         return YES;
     }
+    if (menuItem.action == @selector(removeAllPins:)) {
+        return self.mapView.annotations.count;
+    }
     if (menuItem.action == @selector(showShortcuts:)) {
         return YES;
     }

platform/osx/app/MainMenu.xib

@@ -476,6 +476,12 @@
                                     <action selector="dropManyPins:" target="-1" id="Rtv-8N-3Z8"/>
                                 </connections>
                             </menuItem>
+                            <menuItem title="Remove All Pins" id="6rC-68-vk0">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <connections>
+                                    <action selector="removeAllPins:" target="-1" id="NRM-y5-Wul"/>
+                                </connections>
+                            </menuItem>
                         </items>
                     </menu>
                 </menuItem>

platform/osx/src/MGLMapView.mm

@@ -479,6 +479,10 @@ public:
     }
 }
 
++ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key {
+    return [key isEqualToString:@"annotations"] ? YES : [super automaticallyNotifiesObserversForKey:key];
+}
+
 - (void)setDelegate:(id<MGLMapViewDelegate>)delegate {
     _delegate = delegate;
     
@@ -1412,6 +1416,8 @@ public:
         return;
     }
     
+    [self willChangeValueForKey:@"annotations"];
+    
     BOOL delegateHasImagesForAnnotations = [self.delegate respondsToSelector:@selector(mapView:imageForAnnotation:)];
     
     std::vector<mbgl::PointAnnotation> points;
@@ -1482,6 +1488,8 @@ public:
         }
     }
     
+    [self didChangeValueForKey:@"annotations"];
+    
     [self updateAnnotationTrackingAreas];
 }
 
@@ -1544,18 +1552,19 @@ public:
         NSAssert(annotationTag != MGLAnnotationTagNotFound, @"No ID for annotation %@", annotation);
         annotationTagsToRemove.push_back(annotationTag);
         
-        _annotationContextsByAnnotationTag.erase(annotationTag);
-        
         if (annotationTag == _selectedAnnotationTag) {
             [self deselectAnnotation:annotation];
         }
-        
         if (annotationTag == _lastSelectedAnnotationTag) {
             _lastSelectedAnnotationTag = MGLAnnotationTagNotFound;
         }
+        
+        _annotationContextsByAnnotationTag.erase(annotationTag);
     }
     
+    [self willChangeValueForKey:@"annotations"];
     _mbglMap->removeAnnotations(annotationTagsToRemove);
+    [self didChangeValueForKey:@"annotations"];
     
     [self updateAnnotationTrackingAreas];
 }