* use `set -e` to abort script execution when error codes fail (and haven't been checked)
* use [[ ]] instead of [ ] or test.
* use ROOTDIR/BUILDDIR variables for better readability
* use mktemp in order to avoid accidental name clashes.
* use `make install` instead of `install ...` as cleaner installation process
* this however doesn't install soltest anymore, which I believe is
right, as normal users should not need it installed in their system.
Those who want to run the test suite, can do so manually
* allow optional passing of more additional custom args to cmake