Invoke pylint from Makefile
Makefile: invoke pylint only for the files in the package ft4fttsim
Revise import statements

- Delete unused imports.
- Put imports at the top of each corresponding module.
Add docstring for simlogging module
simlogging.py: changes to silence pylint complaints
simlogging.py: Add a leading underscore to some attribute names
Do not use empty dictionary as default parameter value

This is the same issue as in commit 7a35bbde4cfafbff40e66c67d5a892774038b0e0
Add docstring to networking module
Add and revise docstrings
Remove setter for _Sublink.{transmitter,receiver}_port properties

These property should only be set through the constructor of class _Sublink.
Eliminate classes Port.InputQueue and Port.OutputQueue

We now use simpy.Store instances directly.
Define ethernet constants in a separate module
Delete unused attribute device of class Port
Add missing docstrings to networking module
Rename a few variables and other minor refactorings
Do not use old-style classes
Delete obsolete code and mark class Slave as TODO
Avoid uppercase letters in variable names
Avoid single letter variable names
Add some missing docstrings