Further operator finding fixes

It wasn't finding nonmember operators with a class of the form:

cdef cppclass C:
  C operator+(const C&, int)

(i.e. with the class specified first)

Cython/Compiler/Symtab.py

@@ -838,19 +838,23 @@ class Scope(object):
         
         # look-up nonmember methods listed within a class
         method_alternatives = []
-        if (len(operands)==2 # binary operators only
-            and operands[1].type.is_cpp_class):
-            obj_type = operands[1].type
-            method = obj_type.scope.lookup("operator%s" % operator)
-            if method is not None:
-                # also allow lookup with things defined in the global scope
-                method_alternatives = method.all_alternatives()
+        if len(operands)==2: # binary operators only
+            for n in range(2):
+                if operands[n].type.is_cpp_class:
+                    obj_type = operands[n].type
+                    method = obj_type.scope.lookup("operator%s" % operator)
+                    if method is not None:
+                        method_alternatives += method.all_alternatives()       
         
         if (not method_alternatives) and (not function_alternatives):
             return None
         
+        
+        # select the unique alternatives
+        all_alternatives = list(set(method_alternatives+function_alternatives))
+               
         return PyrexTypes.best_match(operands,
-                                     method_alternatives+function_alternatives)
+                                     all_alternatives)
 
     def lookup_operator_for_types(self, pos, operator, types):
         from .Nodes import Node