New: sort the keys in CPDictionary -description.

This makes it easier to find an item in a large dictionary.

Foundation/CPDictionary.j

@@ -723,10 +723,12 @@ var CPDictionaryShowNilDeprecationMessage = YES,
 - (CPString)description
 {
     var string = "@{",
-        keys = self._keys,
+        keys = [self allKeys],
         index = 0,
         count = self._count;
 
+    keys.sort();
+
     for (; index < count; ++index)
     {
         if (index === 0)