search_global yields record instead of id

It is better for customization to yield record instead of id to prevent to
instantiate a second times the record.

issue4519
review6871002

work.py

@@ -344,6 +344,6 @@ class Work(ModelSQL, ModelView):
 
     @classmethod
     def search_global(cls, text):
-        for id_, rec_name, icon in super(Work, cls).search_global(text):
+        for record, rec_name, icon in super(Work, cls).search_global(text):
             icon = icon or 'tryton-project'
-            yield id_, rec_name, icon
+            yield record, rec_name, icon