Detect unknown option by prefix instead of treating them as parameters

[lefou]

Currently, all paramters not representing a known option are treated as a parameter. With such a (new) configuration option, parameters beginning with a specific prefex (e.g. "-" or "--") could immediatly reported as "unknown option" whereas currently, they would be used as parameter and the application has to validate them later. Of course, this behaviour should be opt-in.