This class allows to load a shader graph from its JSON representation.
To avoid duplicating the shader snippets inside of the JSON which would
be a maintenance nightmare, we instead allow to register a set of node
prototypes by their name and only refer to said names inside the JSON.
Change-Id: I3e7b39e8b3c25f51f331a0a59dda883ac8e2bc57
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
