Add methods to select a node and node contents in a HTML Range

Sources/include/HTMLKitDOMExceptions.h

@@ -17,3 +17,4 @@ extern NSString * const HTMLKitInvalidCharacterError;
 
 extern NSString * const HTMLKitInvalidNodeTypeError;
 extern NSString * const HTMLKitIndexSizeError;
+extern NSString * const HTMLKitWrongDocumentError;