Please decode monitor "EDID" data to text

This bug was originally reported by Paul Wise (pabs@debian.org) in Debian bug #896934:

I recently had occasion to compare two EDID files. I initially tried
diffoscope, saw only a hexdump and then manually compared the files
using a diff of pipes through edid-decode. Subsequently I looked up how
to add new formats to diffoscope and found it was fairly easy.

If the attached patch is acceptable, let me know and I'll push the
OpenPGP-signed version of the commit.

diff -u <(edid-decode /lib/firmware/edid/VGA-1) <(edid-decode /sys/devices/=
pci0000:00/0000:00:03.0/0000:01:00.0/drm/card0/card0-DVI-D-1/edid )

https://en.wikipedia.org/wiki/Extended_Display_Identification_Data