Replace the assert in mel_init to an if statement to address an issue with fuzzing...

Replace the assert in mel_init to an if statement to address an issue with fuzzing. (#1436)

Modified the mel_init code to replace the assert statement with an if statement, returning false when an incorrect sequence of bytes are encountered in the MEL segment.  Similar code should be added to the main MEL decoding subrountine, but the change is more involved; in any case, an incorrect sequence produces incorrect results, but should not be harmful or cause a crash.