bat: Add 'readcapture' option to support analyzing external audio

[tbird20d]

If audio data is captured on another device (ie we are NOT using loopback mode), then allow alsabat to analyze that data, by passing a filename reference on the command line.

Add the '--readcapture' option to the argument parser. When this option is specified, avoid doing a local capture, and instead just read the audio data from the indicated file, and analyze that.

Signed-off-by: Tim Bird [email protected]