Conceptually separated the concept of a parent from an input.
LavPassthroughObject->LavSubgraphObject plus preparation to augment it more
Upgrades to LavSubgraphObject:

- No processing nor computation logic.
- Forwards parents to the output object of the subgraph.
- Forwards get/set input and output calls to the input/output of the subgraph.
Function to configure the subgraph
Remove an unneeded resize call
Change the public API to expose inputs, not parents
Sources take advantage of subgraph functionality to hide internal objects
Merge branch 'bindings' into subgraphs
Convert the rest of the 3d api to subgraphs
For whatever reason, LavSubgraphObject::setInput was unimplemented. Fixed.