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.