automatic unpack of custom extensionObjects(Structures) WORK IN PROGRESS

[oroulet]

fixes:
#373
#293
#287
and is necessary for :
#368

This is a work in progress. Currently only parses the xml file and generate python code which can be compiled online or imported. we need to:

client:

• add a method that parse custom types and registers new classes online

server:

• add a method that generates the xml (to be used in code and by opcua-modeler)
• add a method that create the necessary data types nodes

[zerox1212]

I didn't look too closely at your implementation, but doesn't the spec say that structures can't have nulls?

[zerox1212]

Looks interesting. Only request I would have is to add some doc strings. Especially to StructGenerator methods. Also to be clear, what happens if the struct changes on the server side? Exception? Crash?

Lastly need an example of how to use this.

[oroulet]

This is not ready for release. There is an error, and performance is an issue.....