Add tests

[Rotzbua]

Features

• runs with pre-commit
• add option to autogenerate examples for every box to boxes
• compare generated svg data against checked in data from examples folder
• check for debug output to console

Other changes

• add option to autogenerate examples with boxes --examples
• format list output to console
  • new
  • old

Todo

• [x] add note to PR / docu

Reference

Previous attempt #506

[florianfesti]

I guess I'll just merge and we see how annoying it is to keep the examples up2date.