Add 2019/diels-grabsch2/try.sh script

The try.sh script looks for sha512sum and shasum. If either of these are
found it will use the one found (in the order of sha512sum first and
shasum -a 512 second) and prog. If neither can be found it uses just
prog. If one of them can be found, however, it shows how the output is
the same.

The prog.c was restored from prog.orig.c. Like 2019/diels-grabsch1 the
purpose is no longer valid and even more problematic is the fact that
the checksum value obviously would not be correct otherwise. Makefile
updated instead.

The README.md file has been format/typo checked.

.gitignore updated - added files that try.sh script uses (though it does
delete them after use).

thanks-for-help.md

@@ -4154,10 +4154,11 @@ having tarballs for each individual entry as a convenience.
 
 ## <a name="2019_diels-grabsch2"></a>[2019/diels-grabsch2](/2019/diels-grabsch2/prog.c) ([README.md](/2019/diels-grabsch2/README.md]))
 
-[Cody](#cody) made the author's statement that the entry compiles cleanly true by fixing
-`warning: a function declaration without a prototype is deprecated in all
-versions of C` (in main()). Not strictly necessary but if he's making fixes he
-might as well.
+[Cody](#cody) added the [try.sh](/2019/diels-grabsch2/try.sh) script. This
+script will try and show the difference (i.e. the same output) between the
+program and the result of `sha512sum` or `shasum -a 512` if either of those
+tools can be found but otherwise it'll just run the program itself, showing its
+own sha512sum value.
 
 
 ## <a name="2019_dogon"></a>[2019/dogon](/2019/dogon/prog.c) ([README.md](/2019/dogon/README.md))