Redo issue with PluginStateValueTree. SetPropertyAction & excludeListener

[t0m]

AudioProcessorValueTreeState & UndoManager usage

https://github.com/WeAreROLI/JUCE/commit/2e51654958df26d9c374e961758180cc842e0dfa This commit should address the issues using an UndoManager with an AudioProcessorValueTreeState. An undoable action is no longer pushed onto the stack when the plug-in is loaded Redoing actions works correctly New transactions are started when you interact with an attachment Since this alters the behaviour of the UndoManager this is technically a breaking change, but I doubt anyone was relying upon the old way …