They were suffering from double-connection syndrom, and the way muting worked was now conflicting with how the output sound level setting works
Fixes#1442
Load the setting's cameria preview opengl context lazily and destroy it when done. Only preallocte Core's video buffer if we have any calls active, free up when all calls are done
Toxcore would incorrectly report the call as a video call in the call settings, and then crash while trying to send a video frame in the audio call. We workaround that by using another API that correctly reports the type of the call