small changes to help typing

[Christian-B]

Removed unused stuff

• CamelCaseConfigParser default in init
• MultipleValuesException remove default Nones

Renaming variables to help mypy

• match to full_match

Initialise with a fake value rather than None to avoid Optional and assert Not None

Change the order of params so one can be non optional

Wrap an Iterable[str] with list

• This is needed as Itertable[str] can be both a str or a list of Str so the typer must use MutableSequence[str]

Return None directly

• rather than setting a temp value None and the returning that

raise an exception at the end of methods that should have already returned