[test] make runtest.py executable

See merge request !604

(cherry picked from commit fe45cd56)

1eeac329 [test] make runtest.py executable

Changing `PATH` to `FOLDER` should make things clearer.

Do not offer possibility for user input

[bin] Add script to extract a module based on specific source files, add file to extract the versions of the used modules

* Add possibility to choose variables also by name, instead of only by column

E.g for two plot-over-lines.

* Automatically set the UG path in the *.opts files.
* Remove gstat from *.opts file. Is found automatically, if located in external folder.

Patch has been applied upstream

The installexternal.sh script can be used to install opm
and ert and to apply patches to opm-common and opm-parser.

Move all testing related scripts to subfolder testing

Add subfolders codeutil and doc

We still need to patch Dune-multidomaingrid. Since we anyway need
to patch, the issue with GCC 6 can also be solved by the patch.

Thanks to Thomas for noticing.

The installexternal script is updated to fetch and build the correct Opm
modules.

No patch is required anymore for dune-multidomaingrid. In order to keep that
situation, add `#include <numeric>` to the problem files of the multidomain
tests. This is required if the tests are built with GCC 6.

Adapt README files.

* add dune-alugrid
* add dune-foamgrid
* correct remote urls