fascinatemtd: clean up proprietary file extraction script

 * add proper quoting to variable expansions
 * send error messages to stderr
 * use printf to avoid portability issues with echo
 * don't silently fail when there is an error
 * don't assume the script is run from the directory containing the
   script
 * filter out whitespace-only lines in proprietary-files.txt
 * properly handle whitespace in filenames
 * log progress

Change-Id: I9723cd8d35b0cada8c685aec52f7417b7e595d22