Alert user to drop-outs during recording...

1) When the program detects this, insert zeroes into the recording to keep the
other good parts synchronized.

2) When recording stops, a message box alerts the user, and a label track is
added showing the lost parts, labelled with consecutive numbers.

3) A menu item visible in alpha builds only is added to Tools, to simulate
recording errors at random times and test the reporting feature.

src/RingBuffer.h

@@ -24,6 +24,7 @@ class RingBuffer {
 
    size_t AvailForPut();
    size_t Put(samplePtr buffer, sampleFormat format, size_t samples);
+   size_t Clear(sampleFormat format, size_t samples);
 
    //
    // For the reader only: