Graph / AudioGraph libs: fix for crashes caused by errantly trying to assign NULL to a TTObject
Foundation lib: the method delivering notifications in a way that would avoid feedback loops was broken.  This new method actually works, at least as long as we aren't deleting objects from multiple threads at the same time.
DSP: Addressing deprecation warnings and other issues in TTAudioSignalArray, including adding support for it to the TTAudioObject wrapper.
Graph lib: taking care of deprecation warnings.
AudioGraph lib: addressing deprecation warnings