fix operator overloading for ResNum (to make it compile with gcc 4.3)

modules/mol/base/pymod/export_residue.cc

@@ -113,6 +113,10 @@ void export_Residue()
     .def(self<=self)
     .def(self==self)
     .def(self!=self)    
+    .def(self+=self)
+    .def(self-=self)
+    .def(self+self)
+    .def(self-self)
     .def(self+=int())
     .def(self-=int())
     .def(self+int())

modules/mol/base/src/residue_prop.hh

@@ -28,9 +28,10 @@ namespace ost { namespace mol {
 
 class DLLEXPORT ResNum: private
     boost::additive<ResNum, int,
+    boost::additive<ResNum,
     boost::totally_ordered<ResNum, 
     boost::totally_ordered<ResNum, int,
-    boost::unit_steppable<ResNum> > > >
+    boost::unit_steppable<ResNum> > > > >
 {
 public:
   ResNum(int n):
@@ -74,16 +75,6 @@ public:
     num_-=r.num_;
     return num_;
   }
-
-  ResNum operator+(const ResNum& r)
-  {
-    return ResNum(num_+r.num_);
-  }
-  
-  ResNum operator-(const ResNum& r)
-  {
-    return ResNum(num_-r.num_);
-  }
   
   ResNum& operator++()
   {