Simplify the expected-output class hierarchy in the test suite by using
method overriding instead of implementing all behaviours in the base class
controlled by a set of flags.

* subversion/tests/cmdline/svntest/verify.py
  (ExpectedOutput): Change to a new-style class definition so that diamond-
    shaped inheritance works predictably for the UnorderedRegexOutput class.
    Raise a more informative exception in the unimplemented __cmp__ method.
    Move all regex support to RegexOutput.
  (RegexOutput): Override methods here to implement regex-specific
    behaviour.
  (UnorderedOutput): Move all regex support to UnorderedRegexOutput. Remove
    the (unimplemented) __cmp__ method as it is already inherited.
  (UnorderedRegexOutput): Override methods here to implement regex-specific
    behaviour.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1443190 13f79535-47bb-0310-9956-ffa450edef68