Fix -Woverloaded-virtual= warnings (#39)

Author: jschueller

src/Interfaces/BonOsiTMINLPInterface.hpp

@@ -1011,6 +1011,7 @@ void getBendersCut(OsiCuts &cs, bool global);
     virtual CoinMessageHandler* clone() const{
       return new OaMessageHandler(*this);}
     /** print an OsiRowCut.*/
+    using CoinMessageHandler::print;
     void print(OsiRowCut &row);
   };
   void setOaMessageHandler(const CoinMessageHandler &handler){

src/Interfaces/BonRegisteredOptions.hpp

@@ -68,6 +68,7 @@ class BONMINLIB_EXPORT RegisteredOptions: public Ipopt::RegisteredOptions{
     }
 
    //DECLARE_STD_EXCEPTION(OPTION_NOT_REGISTERED); 
+   using Ipopt::RegisteredOptions::SetRegisteringCategory;
    /** Set registering category with extra information.*/
    void SetRegisteringCategory (const std::string &registering_category,
                                 const ExtraCategoriesInfo extra){