Also fixes the executable bit; now 644.
Replace tabs followed by xmlstarlet format:

```sh
#!/usr/bin/sh

tmpfile=$(mktemp /tmp/xmlformat.XXXXXX)

sed 's/\t/    /g' ${1} > ${tmpfile} && mv ${tmpfile} ${1}
xmlstarlet fo -s 4 ${1} > ${tmpfile} && mv ${tmpfile} ${1}

rm -rf ${tmpfile} # if something goes wrong
```

influence of g was neglected with zero density,
now density (solid and fluid) is 1, gravity is 0,
result is the same

Johannes Herfurth authored Apr 24, 2019 and Dmitry Yu. Naumov committed Jun 14, 2019

Selection of tests published in the benchmark-books

The lower order pressure variable didn't correctly work with the Neumann BC.
The change is not influencing the results.

Cleanup the parameters.