meteclasses 2.x/3.x compatibility

[andrew cooke]

What I do in Lepl is use two stages.  The first calls the type/metaclass directly and the second subclasses that.  This avoids using the "sugar" that changes between 2 and 3.

So, for example, in http://code.google.com/p/lepl/source/browse/src/lepl/matchers/matcher.py#40 I have

  _Matcher = ABCMeta('_Matcher', (object, ), {})

and then

  class Matcher(_Matcher):
      ...

Andrew