Fixed audio preferences settings
In addition to be able to select which device to use for audio input and output this release also fixes an annoying bug on the Tx side when using audio input: Audio input behaves slightly differently than audio output and when the audio engine is started the volume is forced to a value that by default is maximum (1.0). This is not always desirable and using this control you can set it at a lower level (0.00 to 1.00 in 0.01 steps).