

v0.2.5:

    * make raise_error() inject the new error back into the error-handling
      machinery; to get the old behaviour, just raise the error directly.

v0.2.4:

    * speed up invocation of functions within a restart context, by replacing
      the _cur_calls CallStack with a custom control-flow exception.
    * compatability with psyco's simulated stack frames; just make sure you
      import psyco first or call withrestart.callstack.enable_psyco_support().

v0.2.3:

    * speed up establishment of handlers and restarts, by using _getframe(n)
      instead of explicitly walking up the call stack.
    * invoke default handlers only if no other handler has been established.
      Previously they were invoked if no other handler invoked a restart.
      This required some significant changes to how handlers are invoked,
      but none of that should leak into the public API.

v0.2.2:

    * implement logic for the "skip" restart by raising an ExitRestart
      exception rather than by returning NoValue; this makes the non-local
      control flow more explicit.
    * add a "default_handlers" attribute to RestartSuite.  Setting this to a
      Handler or HandlerSuite instance will cause those handlers to be invoked
      if control passes cleanly through all other handlers.

v0.2.1:

    * make CallStack drop references to stack frames once they have exited,
      to avoid creating lots of uncollectable garbage.

v0.2.0:

    * cleanly support yielding from within a restart context; previously
      this would leave the generator's retarts active.
    * require handlers to explicitly raise InvokeRestart(); this makes the
      non-local control flow more explicit.
    * add a proper RestartSuite class for grouping several restarts into
      a single context:
          * the RestartSuite is returned when entering its context, and
            can be used to invoke functions within the scope of only those
            restarts that it contains.
          * the decorator syntax for adding restarts is now a normal method
            on the RestartSuite object.
    * add a proper HandlerSuite class for grouping several handlers into
      a single context:
          * the decorator syntax for adding handlers is now a normal method
            on the HandlerSuite object.

