(re-)import audio graph settings from tracktionedit file

[atsushieno]

After compiling project into *.tracktionedit file, what often happens to me is that I check the results on Tracktion Waveform, try some other audio plugin instruments, and set up exactly the same thing on another AudioPluginHost to generate *.filtergraph file as a new input to augene. It is waste of time. If I could directly import back audio plugin settings from *.tracktionedit, then I could just keep manipulating the plugin UIs on Waveform, save the changes, and re-compile.

Having source and destination on the same file is worrisome, but it's not critical if (1) we store *.tacktionedit files on VCS (git etc.), and/or (2) we generate intermediate backup files when we interpret those plugin settings either from *.filtergraph or *.tracktionedit.