Erroneous flags are passing silently.

[mikeraiko]

My students working with VarScan constantly missing variatns, just providing erroneous flags (say, --min-var-frequency instead of --min-var-qreq). And it passes silently, without any warning. Can you please add this check, just to make the VarScan yell at user if it provides unexisted flags? It can save a lot of time and efforts.

Best,
Mike