fixes for OLE automation. Ref:#76.
NIL option for parameters 'par' and 'ret' in CtlT.OutObject.Invoke added.
NIL test added in CtlC.RetObj.
As proposed by Eugene Temirgaleev in CPC 1.7 rc5.
In addition, the docu for CtlT has been updated.

Signed-off-by: Josef Templ <josef.templ@gmail.com>