AudioGraph xcode project: fix for reverse make args
TTAudioEngine: getting to compile as an extension now that it is factored-out from the DSP lib.
AudioGraph: beginning to adjust the code to deal with TTAudioEngine now longer being in the DSP lib.
TTDictionary: adding convenience templates to wrap value getting for non-native types, as well as making TTSymbol args pass-by-value instead of pass-by-reference.