Add One2One field

tryton/gui/window/view_form/view/list_gtk/parser.py

Index: tryton/gui/window/view_form/view/list_gtk/parser.py
===================================================================
--- a/tryton/gui/window/view_form/view/list_gtk/parser.py
+++ b/tryton/gui/window/view_form/view/list_gtk/parser.py
@@ -572,6 +572,9 @@
         else:
             return False, None
 
+class O2O(M2O):
+    pass
+
 class UnsettableColumn(Exception):
 
     def __init__(self):
@@ -911,4 +914,5 @@
     'sip': Char,
     'progressbar': ProgressBar,
     'reference': Reference,
+    'one2one': O2O,
 }