Asana tasks!

See https://app.asana.com/0/11724913287040/14477880045173

- improve README.md https://app.asana.com/0/11724913287040/14477880045175
- use `@label@` to label shortcuts, objects and other things in `graph_objs_meta.py` https://app.asana.com/0/11724913287040/14477880045183
- table of content resides `graph_objs_meta-toc.py`

- and more (see commits)
You might want to pull this into a 'contributing.md' file? GitHub recognizes such a file and will throw up a nice banner when someone wants to contribute. This is how I did it in the plotly/python-api repo. Then you can just link to this file in the `readme.md`.