Avoid conflicting signal registrations when run under mod_wsgi. Allows the use of `WSGIRestrictSignal Off` (LP #681853).

The locking here was only ever needed for the old `regex` module that was
originally used for this code, but that was replaced by the thread-safe `re`
some 10 years ago (see r20110, april 2001).

Use the cookie APIs or addHeader instead.

  order : tids were stored and retrieved as dictionary keys. 

Reintroduce an aq_inner into the getPhysicalPath code to fix test failures in CMF's discussion items

Optimized the `OFS.Traversable.getPhysicalPath` method to avoid excessive amounts of method calls. Thx to Nikolay Kim from Enfold

Removed the `App.version_txt.getZopeVersion` API, you can use ``pkg_resources.get_distribution('Zope2').version`` instead. Zope2's own code only calls the `version_txt` function returning a string.