todo

performance matters, do benchmark
intersection for arbitrary path: https://stackoverflow.com/questions/26490861/find-intersection-of-svg-path
support shapes: ellipse, diamond, round corner rect(as rect's attribute?)
allows shapes as extensions, so that every one can contribute
- for example: an user shape, a database shape: http://c4model.com/
- don't limit the system to some common shapes. allow any as shape.
- so we should draw rect, circle...etc as path, in order to be generic??
postprocess elkGraph, remove unnecessary props
styleOptions, such as border color, dotted line edge
Auto generate layoutOptions: { 'elk.position': '(1,0)' } so nodes are in order.
- Should take direction into consideration.

How to enable log

import * as logLevel from 'loglevel'

logLevel.getLogger('ariel/index').setLevel('DEBUG')