Use right method name to inherit start-editing on CellRenderer Float/Integer

Since changeset c77863df6c24, the renderer inherits implicitly of
gtk.CellRendererText instead of gtk.GenericCellRenderer

issue5234
review17731002

tryton/common/cellrendererfloat.py

@@ -12,9 +12,9 @@ class CellRendererFloat(CellRendererInteger):
         super(CellRendererFloat, self).__init__()
         self.digits = None
 
-    def on_start_editing(self, event, widget, path, background_area,
+    def do_start_editing(self, event, widget, path, background_area,
             cell_area, flags):
-        editable = super(CellRendererFloat, self).on_start_editing(event,
+        editable = super(CellRendererFloat, self).do_start_editing(event,
             widget, path, background_area, cell_area, flags)
         editable.connect('key-press-event', self.key_press_event)
         return editable

tryton/common/cellrendererinteger.py

@@ -7,9 +7,9 @@ import locale
 
 class CellRendererInteger(CellRendererText):
 
-    def on_start_editing(self, event, widget, path, background_area,
+    def do_start_editing(self, event, widget, path, background_area,
             cell_area, flags):
-        editable = super(CellRendererInteger, self).on_start_editing(event,
+        editable = super(CellRendererInteger, self).do_start_editing(event,
                 widget, path, background_area, cell_area, flags)
         editable.set_alignment(1.0)
         editable.connect('insert_text', self.sig_insert_text)