fixes #158: add support for callout subtitle via annotation subtitle

@@ -62,6 +62,9 @@
 /** The annotation's title. */
 @property (nonatomic, retain) NSString *title;
 
+/** The annotation's subtitle. */
+@property (nonatomic, retain) NSString *subtitle;
+
 /** Storage for arbitrary data. */
 @property (nonatomic, retain) id userInfo;
 

@@ -38,6 +38,7 @@
 
 @synthesize coordinate;
 @synthesize title;
+@synthesize subtitle;
 @synthesize userInfo;
 @synthesize annotationType;
 @synthesize annotationIcon, badgeIcon;
@@ -65,6 +66,7 @@
     self.mapView      = aMapView;
     self.coordinate   = aCoordinate;
     self.title        = aTitle;
+    self.subtitle     = nil;
     self.userInfo     = nil;
     self.quadTreeNode = nil;
 
@@ -86,6 +88,7 @@
 - (void)dealloc
 {
     self.title        = nil;
+    self.subtitle     = nil;
     self.userInfo     = nil;
     self.layer        = nil;
     [[self.mapView quadTree] removeAnnotation:self];

@@ -1705,7 +1705,8 @@
 
         _currentCallout = [SMCalloutView new];
 
-        _currentCallout.title = anAnnotation.title;
+        _currentCallout.title    = anAnnotation.title;
+        _currentCallout.subtitle = anAnnotation.subtitle;
 
         if (anAnnotation.layer.leftCalloutAccessoryView)
         {