Change width from width per section and number of sections to proper
section parameter sx.
Use more generic parameter names.
Make finger holes configurable.
Add optional lid topper to get a plain surface on top.
Previously box was one thickness to low as the height of the lid was not
accounted for.
Thanks to hd (https://hackaday.io/hacker/1210037-hd) for pointing this
out!
Having this call there was necessary in the past as the open() method would
need the canvas size as a parameter. This is now determined automatically
after rendering.
Still calling open() is deprecated but won't result in an error.