A conversion script for files in .m4a format (iTunes) to .aac

This script converts .m4a files to .aac files from a source path
to a target path creating subdirectories that existed in the source
and replicating the directory structure to the target.

Example execution:
m4a2aac "/Volumes/Media/iTunes Library/Music" "/Volumes/Media/processed"

It has three options, -h for help, -d to turn on debugging and
-n to specify no conversion, just display what it would do