TTAudioSignalArray::setSignal() implementation moved out of the header and into the c source file.  As a result the deprecation warnings therein are quarantined to the building of the DSP lib and don't pollute every single project with a dependency on DSP.
TTObject: a change to the preferred method of sending messages (the old method of sending messages still works).  Now you pass the input as an arg (as before) but the output comes back as the return value of the method.  This opens the doors for a number of interesting possibilities in terms of graph construction and direct calls that previous was clumsy (at best).