Code refactoring

[m1ch]

I did a cleanup of the code and removing all compatibility to python < 3.8. m1ch:bCNC

Getting a good insight in the code now, I propose to do some major refactoring as well:

• Defining 3 major python packages:

  • Core ... all basic functionality like G-code generation, etc.
  • Sender (or Com) ... all functionality that has to do with the communication with the controller
  • GUI ... ever functionality that has to do with the GUI. No direct G-code generation, or sender calls from the GUI anymore. All calls shall be done via the Core.

• Re-definition of plugins:

  • Plugins shall be code provided by the bCNC community and not necessary by the bCNC maintainers.
  • Some plugins now are core functionality in my opinion. For example flatten, drilling, etc. Move them to core.
  • New controllers can also be plugins.
  • Also, new senders can be plugins in future ( ie. direct IP communication)

[JipeB]

Hello,
Code cleanup is a very good thing, but it's going to have to fix a major bug that prevents bCNC from working with a decent manual tool change.
Moreover, the current interface, by its lack of intuitiveness, discourages newcomers whose only benchmarks are Wikis that are often obsolete or biased. see #1775
JP