#1 Assertion failure handling of wx apps under test

[Reinhold Füreder]

At least with wxWidgets 2.8.7, but presumably much earlier the (optional) assertion failure interruption handling of wx applications under test does not work as expected anymore: a minor refactoring in wx needs to be applied to the class WxGuiTestApp -- OnAssert(...) is now called OnAssertFailure(..., func, ...) with an additional parameter.