Nodes were previously written to be "strongly typed" in that a parameter's
"type" enforced whether it could be connected to another. All code related
to that has now been removed since not only is it hard to maintain and
likely unnecessary, it's possible the nodes will work differently later on
anyway.
Rather than convoluting the MediaInput node, te MediaInput is now an abstract
base class that provides access to a Decoder and derived classes are
responsible for handling it