Do some heavy clean up in ZopePageTemplate which gets rid of a lot of temporary

hacks that were in there before.  Tried to reduce the diff to the Zope 2.9 code
a little and moved some content type guessing code to PageTemplateFile where it
really belongs (that also avoids a circular import problem).

lib/python/Products/PageTemplates/PageTemplateFile.py

@@ -25,12 +25,18 @@ from Shared.DC.Scripts.Script import Script
 from Shared.DC.Scripts.Signature import FuncCode
 from Products.PageTemplates.Expressions import SecureModuleImporter
 from Products.PageTemplates.PageTemplate import PageTemplate
-from Products.PageTemplates.ZopePageTemplate import guess_type
 
 from zope.contenttype import guess_content_type
+from zope.pagetemplate.pagetemplatefile import sniff_type
 
 LOG = getLogger('PageTemplateFile')
 
+def guess_type(filename, text):
+    content_type, dummy = guess_content_type(filename, text)
+    if content_type in ('text/html', 'text/xml'):
+        return content_type
+    return sniff_type(text) or 'text/html'
+
 class PageTemplateFile(SimpleItem, Script, PageTemplate, Traversable):
     """Zope 2 implementation of a PageTemplate loaded from a file."""
 

lib/python/Products/PageTemplates/tests/testZopePageTemplate.py

@@ -12,7 +12,6 @@ import Zope2
 import transaction
 
 from Testing.makerequest import makerequest
-from Products.PageTemplates.ZopePageTemplate import _default_content_fn
 
 class ZPTRegressions(unittest.TestCase):
 
@@ -35,7 +34,7 @@ class ZPTRegressions(unittest.TestCase):
 
     def testAddWithoutParams(self):
         pt = self._addPT('pt1')
-        default_text = open(_default_content_fn).read()
+        default_text = open(pt._default_content_fn).read()
         self.assertEqual(pt.title, '')
         self.assertEqual(pt.document_src().strip(), default_text.strip())