HACK: make PropertyGetter a new style class

We have in ZODB some PropertyGetter as new style classes (there are also
some cases in the XML exports in the repo, search for _dt_reconstructor
)

product/ERP5Type/Accessor/Constant.py

@@ -32,7 +32,7 @@ from Accessor import Accessor
 # Creation of default constructor
 class func_code: pass
 
-class PropertyGetter:
+class PropertyGetter(object):
   """
   This is class is mostly used in order to handle compatibility
   issues when we wish to make a property a method. For instance,
@@ -43,7 +43,7 @@ class PropertyGetter:
   func_code.co_argcount = 0
   func_defaults = ()
 
-  def __init__(self, id, value=None):
+  def __init__(self, id=None, value=None):
     self._id = id
     self.__name__ = id
     self.value = value