shellcheck: run_calltool.sh issues

Shellcheck (​​​​​https://github.com/koalaman/shellcheck) finds the following issues:

In run_calltool.sh line 18:
  python -m calltool $calculation > callgraph/$calculation
                     ^-- SC2086: Double quote to prevent globbing and word splitting.
                                              ^-- SC2086: Double quote to prevent globbing and word splitting.


In run_calltool.sh line 21:
echo <<EOF > callgraph/README
^-- SC2217: Redirecting to 'echo', a command that doesn't read stdin. Bad quoting or missing xargs?