Constructor OptionAttribute(char, string) although property ShortName is string

[HelOWeen]

The current constructor of OptionAttribute only allows for 1 character shortName, although the property ShortName itself is of type string. Which prevents us from creating options with more than 1 character, though that might be useful in order to make the short name parameter name of similar options (more) memorable for the user, e.g.

"fn", "filename"
"fs", "filesize"