Automatically enable font smoothing at start-up

If font smoothing is not enabled, enable it for the life of the program.
Restore the original setting upon exiting.
Minor coding style improvements
Prompt user to download ExifTool if missing
Implement sub-group metadata recording
Initial build of metadata browser

Quite nice for a first draft, I think.  Lots of little things left to
tweak and improve, but at least this allows me to check the metadata to
make sure I'm parsing it right!