A bigger set of changes to Config

[isotopp]

A sequence of commits that changes class Config step by step:

• cleaned up help/print_help logic, deleting unused variables.
• methods are now typed, so are instance variables.
• A lot of boolean logic cleanup (no parens around if conditions, no "if bla is True" when "if bla" is fine.
• A fix to the sample config file, which accidentally includes invalid protocols in forbidden_websites.

For some reason this commit is in conflict with a previous change, but it seems to be okay to just accept this version.

[isotopp]

Fixed conflicts.

[andreasscherbaum]

FTR: I don't like the compact Python syntax with no spaces and no parentheses. But I see that your linter is complaining, so let's pass that.