py2/py3: import InstanceDict from DocumentTemplate._DocumentTemplate instead of deprecated DocumentTemplate.DT_Util.

If we have a portal_type definition and its instances in the same Business Template,
_importFile() creates broken objects in PathTemplateItem._objects for such instances and
they will be 'fixed' in install() timing. But in Python 3, it does not work because :

while importing a content file, like *.js...

(BusinessTemplate.py)
     try:
       setattr(obj, property_name, data)
     except BrokenModified:
       obj.__Broken_state__[property_name] = data # <-- !!!
       obj._p_changed = 1

obj.__Broken_state__ access here also raises BrokenModified.

while importing an XML file...

(ZODB/broken.py)
    def __new__(class_, *args):
        result = object.__new__(class_) # <-- !!!
        result.__dict__['__Broken_newargs__'] = args
        return result

we get an exception 'TypeError: object.__new__(Portal Type) is not safe, use Base.__new__()'

(not yet for scripts under portal_skins)

in Python 2, _aq_dynamic() returns None without try..except but it raises ValueError in Python 3.

(python 2)
> /SR/parts/erp5/product/ZSQLCatalog/Extensions/zsqlbrain.py(31)_aq_dynamic()
 31  ->   def _aq_dynamic(self, name):
 32         """Acquire an attribute from a real object.
 33         """
 34         if name.startswith('__') :
 35           return None
 36         return getattr(self.getObject(), name, None)
((Pdb)) getattr(self.getObject(), name, None)
*** ValueError: Unable to getObject from ZSQLBrain if ZSQL Method does not retrieve the `path` column from catalog table.
((Pdb)) r
--Return--
> /SR/parts/erp5/product/ZSQLCatalog/Extensions/zsqlbrain.py(36)_aq_dynamic()->None # <-- !!!