[x3d-public] Give Input, using python decorators

[John Carlson]

Here's the kind of thing I'd like to see with dict-based (not strings) 
scenes in python:

https://stackoverflow.com/questions/27342149/decorator-execution-order

I use it within the context of converting between encodings and SAI scenes.

The idea would be to take an X3D-standard dict, convert it to a 
json-dict, then to json using the standard python package, and also the 
reverse path.

Ditto with VRML, DOM, XML, EXI, PKI, etc. etc.

Then we can repurpose this architecture to XSLT, JavaScript, etc.

We should be able to stack decorators to create converters between dicts.

So we achieve a UNIX-like philosophy with decorators, I hope.

John