UndoManager and UndoableAction tweak

Would be extremely cool if the UndoManager::perform and UndoableAction::perform/undo return the handy juce::Result class instead of a meaningless boolean. This way we can avoid to dynamic_cast each action to know what has gone bad in the last action.

makes sense ?

Well, it would possibly make sense if it didn't mean that everybody would have to re-write every single UndoableAction class that's out there!

pity. let's wait for juce 4 then ;)