generate extension based graphics based on drawio extensions.js

active? flag on page defaulting to true. set to false to exclude page from diagram.

first level child nodes need to hang of node 1

node has child nodes and add_node will set a nodes parent

nodes can belong to a parent node, the top level node responds with truthy to root?

add sample diagram for the github readme file

write samples into docs folder and display in readme

add export as .PNG, needs to take a page number as the PNG will not support multiple pages

add export as .SVG, needs to take a page number as the SVG will not support multiple pages

add save as .drawio