Missing unused parameter warning for `ref` parameter

[andy-hanson]

When I run dub run dscanner -- --styleCheck app.d on this code, there is only a warning for the parameter passed by-value.

private:
void f(ref int i) {}
void g(int j) {}

Output:

app.d(3:12)[warn]: Parameter j is never used.

i is similarly unused, so I would expect to get a warning for it too.