It is planned to add another matrix type for the tests.
The names of the prepare routines have become a bit inconsistent and
confusing. Thus the rename

Anything if it makes Andreas happy :)

We got reports from a user that there were troubles with certain domain
decompositions. So far the tests only looked at (approximately) square
decompositions in column-major process order.

Now, a new class of tests loops over all possible decompositions
(row * col) for a given number of total tasks.

So far, we can not confirm that there are any problems, all
possibilities work as expected.

Previously we checked ortonormality of eigenvectors by comparing
the matrix S^T * S to identity matrix. The new feature is also
checking just the diagonal of the matrix S^T * S. By that we get
the information, how far are the eigenvectors from having length 1.
If it turns out to be important, we could try to normalize them
at the end of elpa, which is simple (in contrast with enforcing
better orthogonality).

- Remove all use of ELPA internal modules, the test programs now
  only use the public ELPA API. This is now enforced, by hiding the
  private modules

- Prefix all test internal modules with "test_" to make it really
  clear that these modules are not to be used by users.

The legacy API is has been (internally) ported to use the new interface.
The intent is that users of the legacy API do not have to change their
codes.

Next step is to completely adapt the .gitlab-ci.yml file

They are in a sad state, it's all copy&paste and chaos. This commit
only touches the surface so far.

gpu tests for elpa 1 added

Conflicts:
	src/elpa1.F90
	src/elpa1_tridiag_real_template.X90
	src/elpa_c_interface.F90
	test/Fortran/test_complex.F90
	test/Fortran/test_complex_single.F90
	test/Fortran/test_real.F90
	test/Fortran/test_real_single.F90
	test/Fortran/test_real_with_c.F90