Add option to identify / ignore HEIF formatted files

[YLSnewb]

While trying to process millions of JPEGs, more recent files that are labelled as JPEGs are actually HEIF files. I've also encountered what seems like a JPEG wrapped in a TIFF file, which I'd also like to see pass through the process unchanged.

Rather than bail out with a non-zero return code, I'd like the option of simply doing nothing, or merely copying the HEIF file to the 'outfile' named file.