Serializer/Deserializer

Hi,

So, since last time, I have added a new class "CanvasSerializable", which is a direct subclass of "Canvas", except it adds support for serialization.  If every canvas is serializable, then making the serializer work properly is much easier, and allows for better design.

The changes affected a lot of the project, so I changed every single reference to Canvas to CanvasSerializable, and then converted things back that just flat out couldn't be (e.g., GWT callbacks return Canvas[], so I can't upcast them to CanvasSerializable).

This seems to have had an effect already.  The serializer appears to be working properly.  There's still some problems on the server-side (I think) so serializing doesn't quite work.  Because there's no serialized data, naturally, the deserializer doesn't work either.

Hopefully, over the next few posts, the serializer module may be completed!

Ian