Added sorting capabilities to CPTreeNode.

Reviewed by me.

AppKit/CPTreeNode.j

@@ -66,4 +66,17 @@
     return _childNodes[anIndex];
 }
 
+- (void)sortWithSortDescriptors:(CPArray)sortDescriptors recursively:(BOOL)shouldSortRecursively
+{
+    [_childNodes sortUsingDescriptors:sortDescriptors];
+
+    if (!shouldSortRecursively)
+        return;
+
+    var count = [_childNodes count];
+
+    while (count--)
+        [_childNodes[count] sortWithSortDescriptors:sortDescriptors recursively:YES];
+}
+
 @end

Foundation/CPSortDescriptor.j

@@ -59,6 +59,11 @@ CPOrderedDescending     =  1;
     BOOL        _ascending;
 }
 
++ (id)sortDescriptorWithKey:(CPString)aKey ascending:(BOOL)isAscending
+{
+    return [[self alloc] initWithKey:aKey ascending:isAscending];
+}
+
 // Initializing a sort descriptor
 /*!
     Initializes the sort descriptor.
@@ -71,6 +76,11 @@ CPOrderedDescending     =  1;
     return [self initWithKey:aKey ascending:isAscending selector:@selector(compare:)];
 }
 
++ (id)sortDescriptorWithKey:(CPString)aKey ascending:(BOOL)isAscending selector:(SEL)aSelector
+{
+    return [[self alloc] initWithKey:aKey ascending:isAscending selector:aSelector];
+}
+
 /*!
     Initializes the sort descriptor
     @param aKey the property key path to sort