Non-existent parameters to Testplan class do not cause error

[ryan-collingham]

I noticed that adding complete garbage parameters to the Testplan class constructor does not cause an error. E.g.:

import testplan
testplan.Testplan(
    name="MyPlan",
    foobarbaz=True)

I would expect the foobarbaz to cause a TypeError but it does not. This may cause confusion in case of a minor typo of a parameter leading to unexpected behaviour.

I haven't checked but likely this problem isn't specific to the Testplan class itself but might be due to the common configuration validation. It should be set up to raise an Exception if unrecognised parameters are passed.