Useful for detecting when a graph needs recompiling, in tandem with the
"InvalidateCache()" signal when necessary, this signal ripples through the
nodes when any of the connections change which will likely need handling by
the renderer.
Both audio and video renderers were working off the same invalidation signal
(i.e. changing audio would also trigger a re-render of the video). This is
obviously suboptimal and now they are separate.
The new rendering pipeline strives to simplify the nodes themselves as much
as possible and move much of the logic to an external rendering engine. This
change removes all of the responsibilities that no longer belong to the
nodes themselves and will soon be folded into the renderer.
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.