add sample of MyData3

* MyData3.import() worked wrong. Inner Dictionary wasn't deserialized
correctly.
support generic type for key/value

* when deserializing XML, confirm reading node is not EndElement.
change writing of MyData3 instance
add third property "CMYK" in MyData3

* "CMYK" is SerializableDictionary of SerializableDictionary like as
RGB.
* "CMYK" is not deserialized correctly.
break off the reading XML when reaching EndElement