allow implicit conversion from int to ResNum in Python

Fixes BZDNG-111

git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2220 5a81b35b-ba03-0410-adc8-b2c5c5119f08

modules/mol/base/pymod/export_residue.cc

@@ -71,6 +71,7 @@ void export_Residue()
     .def(self+int())
     .def(self-int())    
   ;
+  implicitly_convertible<int, ResNum>();
   {
     scope sec_struct_scope=class_<SecStructure>("SecStructure", init<>())
       .def(init<char>())