If an IDispatch object is returned from in the retval for a propget 
function and an extra parameter was passed in to ITypeInfo::Invoke then 
it should call IDispatch::Invoke on the returned object with the extra 
parameter to retrieve the value of the object, which is then returned in 
pVarResult.

oleaut32: Comment out "dual" attribute of IKindaEnumWidget in tmarshal test to cause the interface to be marshaled correctly.

This fixes a bunch of tmarshal tests.

oleaut32: Fix a one-off test failure in the tmarshal tests - TYPE_E_LIBNOTREGISTERED is an expected return value.

oleaut32: A value of PARAMFLAG_FNONE for wParamFlags means that the parameter is also marshaled and unmarshaled in the PARAMFLAG_FOUT case.

This also makes the headers and implementation more consistent.