Correctly handle allowUnknownOption in .parseOptions()

[aweebit]

Problem

#1945

Solution

Implement the first solution suggested in the issue.

Unknown options are now treated as command-arguments in .parseOptions() as suggested by the docs.

The incorrect test has been removed.

ChangeLog

Fixed

• Breaking: treat unknown options as command-arguments in .parseOptions() as suggested by the docs

[shadowspawn]

The current behaviour is as intended. .parseOptions() is an internal routine not affected by .allowUnknownOption().

See longer explanation of .parseOptions() in issue: #1945 (comment)