Bug#850850: diffoscope: add file type (magic) information to diff output

[Emanuel Bronshtein]

Package: diffoscope
Version: 67
Severity: wishlist

Dear Maintainer,

Please add file-type/magic information for files as this information is useful (in order to know the file content type, especially for binary files without extension)
for example:
https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/diffoscope-results/buildapp.html

The ./usr/bin/buildapp file show "No file format specific differences found inside, yet data differs" without information about the file format.

│   ├── data.tar.xz
│   │   ├── data.tar
│   │   │   ├── ./usr/bin/buildapp
│   │   │   │┄ No file format specific differences found inside, yet data differs
│   │   │   @@ -29602,15 +29602,15 @@
│  00073a10: 2faf 1100 1000 0000 030d 3020 0000 0000  /.........0 ....
│  00073a20: 4505 0006 0000 0000 0000 0000 0000 0000  E...............
│  00073a30: 2455 d0fd 6eae f32f 6fbb 1500 1000 0000  $U..n../o.......
│  00073a40: 1fca 1100 1000 0000 030d 3020 0000 0000  ..........0 ....
│  00073a50: 4505 0006 0000 0000 4f07 0b01 1000 0000  E.......O.......
│  00073a60: 5290 9b22 8608 743b cf07 0b01 1000 0000  R.."..t;........
│  00073a70: efac fd00 1000 0000 0306 3020 0000 0000  ..........0 ....
│ -00073a80: 4505 0006 0000 0000 5802 0000 0000 0000  E.......X.......
│ +00073a80: 4505 0006 0000 0000 5001 0000 0000 0000  E.......P.......
│  00073a90: ea61 b511 6bcf ac33 ef7a 0000 1000 0000  .a..k..3.z......

example where it's available (not diffoscope output)
The "(GNU message catalog (little endian), revision 0.0, 53 messages)" and "(SQLite 3.x database)" in:

https://www.zq1.de/~bernhard/linux/reproducibleopensuse/compare.factory-20170102/acl-compare.out

/usr/share/locale/en at boldquot/LC_MESSAGES/acl.mo differs (GNU message catalog (little endian), revision 0.0, 53 messages)
--- /tmp/tmp.r1ITW1350E/tmp.yUK5LWis29	2016-12-22 16:23:22.050882000 +0000
+++ /tmp/tmp.r1ITW1350E/tmp.aNYlnHr5rm	2016-12-22 16:23:22.050882000 +0000
@@ -293,7 +293,7 @@
 00001240  61 74 65 3a 20 31 39 37  30 2d 30 31 2d 30 31 20  |ate: 1970-01-01 |
 00001250  30 30 3a 30 30 2b 30 30  30 30 0a 50 4f 2d 52 65  |00:00+0000.PO-Re|
 00001260  76 69 73 69 6f 6e 2d 44  61 74 65 3a 20 32 30 31  |vision-Date: 201|
-00001270  37 2d 30 31 2d 30 31 20  30 30 3a 30 30 2b 30 30  |7-01-01 00:00+00|
+00001270  38 2d 30 32 2d 30 33 20  31 31 3a 31 31 2b 30 30  |8-02-03 11:11+00|
 00001280  30 30 0a 4c 61 73 74 2d  54 72 61 6e 73 6c 61 74  |00.Last-Translat|
 00001290  6f 72 3a 20 41 75 74 6f  6d 61 74 69 63 61 6c 6c  |or: Automaticall|
 000012a0  79 20 67 65 6e 65 72 61  74 65 64 0a 4c 61 6e 67  |y generated.Lang|
 
https://www.zq1.de/~bernhard/linux/reproducibleopensuse/compare.factory-20170102/ibus-table-others-compare.out

/usr/share/ibus-table/tables/rusle.db differs (SQLite 3.x database)
--- /tmp/tmp.gVQgyFL8rF/tmp.uMBjPWe4Ik	2016-12-26 07:47:19.060363000 +0000
+++ /tmp/tmp.gVQgyFL8rF/tmp.pgRr4Pg7Ow	2016-12-26 07:47:19.060363000 +0000
@@ -37,11 +37,11 @@
 00000fd0  62 6c 65 69 6d 65 69 6d  65 02 43 52 45 41 54 45  |bleimeime.CREATE|