* Rename the 'Identity' node to 'Passthrough' internally
* Rename the 'Memoize' node to 'Cache' internally
* Let skip_impl proto nodes auto-generate as document node definitions
* Remove the wrapper 'Passthrough' node from document_node_definitions.rs
* Remove the wrapper 'Cache' node from document_node_definitions.rs
* Remove the wrapper 'Monitor' node from document_node_definitions.rs
* Remove the wrapper 'Noise Pattern' node from document_node_definitions.rs
* Remove the wrapper 'Brush' node from document_node_definitions.rs
* Remove the wrapper 'Transform' node from document_node_definitions.rs
* Code review improvements
* Rename Cache node back to Memoize
* More code review