Summary of significant changes:
-Autsave doesn't depend on STREAM_EXTRA3
-Don't risk only saving one compass on copter if CAL_ALWAYS_REBOOT is set
-Only calibrate compasses that are both health and marked for use (there was a inconsistency in handling the mask)
-Fix incorrect failure reporting on DO_ACCEPT_MAG_CAL with a mask of 0 if a channel was specifically not started
-Fix not starting the buzzer if the delay is set to 0 seconds
-Always send MAG_CAL_REPORT until its acknowledged
-Correct the field in MAG_CAL_REPORT for autosave to indicate if the compass had actually been saved, rather then being scheduled to be saved
-Remmove unused public interfaces
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