Portal Type as Classes: Fix memory leak: reset erp5.* classes were never GC (#20170126-19C38D8).

zope.{interface,component} implement Interfaces through __implements__,
__implemented__ (both implementedBy instances) and __provides__ (ClassProvides
instance) attributes set on the class itself through implementedByFallback
(zope.interface.declarations).

However, this implementation creates circular references by referencing the
class itself and thus erp5.* classes (and all its Accessors instances) were
never GC even after a reset.

When running testXHTML and installing the Unit Tests bt5s:
  * After 10 resets:  21MB leak (~  7% of Zope process USS).
  * After 20 resets:  70MB leak (~ 18% of Zope process USS).
  * After 28 resets: 122MB leak (~ 26% of Zope process USS).

product/ERP5Type/dynamic/portal_type_class.py

@@ -373,6 +373,21 @@ def synchronizeDynamicModules(context, force=False):
     try:
       for class_name, klass in inspect.getmembers(erp5.portal_type,
                                                   inspect.isclass):
+        # Zope Interface is implemented through __implements__,
+        # __implemented__ (both implementedBy instances) and __provides__
+        # (ClassProvides instance) attributes set on the class by
+        # zope.interface.declarations.implementedByFallback.
+        #
+        # However both implementedBy and ClassProvides instances keep a
+        # reference to the class itself, thus creating a circular references
+        # preventing erp5.* classes to be GC even when not being actually used
+        # anywhere anymore after a reset.
+        for k in klass.mro():
+          if k.__module__.startswith('erp5.'):
+            for attr in ('__implements__', '__implemented__', '__provides__'):
+              if k.__dict__.get(attr) is not None:
+                delattr(k, attr)
+
         klass.restoreGhostState()
 
       # Clear accessor holders of ZODB Property Sheets and Portal Types
@@ -401,3 +416,12 @@ def synchronizeDynamicModules(context, force=False):
   cache_tool = getattr(portal, 'portal_caches', None)
   if cache_tool is not None:
     cache_tool.clearCache()
+
+  # Clear Zope Component Registries (Zope Adapters/Utilities cache lookup)
+  # because it contains references to reset dynamic classes (which prevents
+  # them from being GC and may create inconsistencies when Interfaces have
+  # been changed)
+  import zope.component
+  gsm = zope.component.getGlobalSiteManager()
+  gsm.adapters.changed(gsm)
+  gsm.utilities.changed(gsm)