Add support for custom names of template instantiation methods.

pybindgen/cppclass.py

@@ -600,13 +600,12 @@ public:
         else:
             raise TypeError
             
-        mangled_name = utils.get_mangled_name(name, method.template_parameters)
         try:
-            overload = self.methods[mangled_name]
+            overload = self.methods[method.mangled_name]
         except KeyError:
-            overload = CppOverloadedMethod(mangled_name)
+            overload = CppOverloadedMethod(method.mangled_name)
             overload.pystruct = self.pystruct
-            self.methods[mangled_name] = overload
+            self.methods[method.mangled_name] = overload
 
         method.class_ = self
         overload.add(method)