Replace messy tests with cleaned-up versions from trunk. The old tests deleted 'Zope2/version.txt' - WTFBBQ?

    
o This move breaks an import cycle in third-party code which avoids imports
  from 'Globals.'
              
o Leave the class importable from its old location without deprecation.

- The level < 0 case is basically the union of all searches for levels 0
  through to max. Just call search() for each level and use multiunion on all
  the results.
- Shorten the 'no-such-path' detection to one test.

into CVS trunk 8 years ago..

o Fix fragile doctest for changed traceback.

o Drop never-releaesed '_seek' feature from
  Products.Five.testbrowser.PublisherMechanizeBrowser.

Backport DateTime test fixes from trunk (due to updated pytz).

'tal:on_error' handler has attributes visible to restricted code.

Add check for doomed transactions in default transaction manager, abort silently if the tm tries to commit a doomed transaction

 - Rather nasty fix to work around Zope 3 exceptions that have more than one positional argument on the constructor. Also, pass 'handle_errors' argument used for functional http testing around and use that on raise_standardErrorMessage to decide if we need to care about rendering a full HTML traceback.