[DCP-o-matic] Crash when quitting while in preferences

It happens regularly in the Mac version (also earlier than the current one) - quitting the program (CMD+Q) while being in preferences, will always crash the application. No big deal, but maybe easy to fix. Also, there seems to be a problem with the audio analysis in the mac version, when you reopen a previously save project - the program seems to assume that an audio analysis has been already performed, but is missing the analysis data. Hence, there is no volume graph. Only solution is to discard the content audio and reloading it - then an analysis will be performed and the graph is there. This also happened in most earlier mac versions I tried this. The current windows version does not have that issue. - Carsten