Add a PCG Node and Parameter

Recommended sequence:

1. pcg.graph.inspect to understand the graph.
2. pcg.palette to find a node creation entry.
3. schema.inspect for pcg.graph.edit operation addFromPalette.
4. pcg.graph.edit to add and connect nodes.
5. pcg.node.inspect before changing node settings.
6. pcg.parameter.inspect before changing graph user parameters.
7. schema.inspect for the selected pcg.parameter.edit operation.
8. pcg.parameter.edit.
9. pcg.compile.

Keep node settings and graph parameters separate. They are different PCG concepts.