yet another attempt to improve single/double and real/complex
unification more readable

with obvious meaning

for easier comparisons of elpa and mkl, a test case using scalapack
function pdsyevd has been added

The MPI communicators were never freed, this created a memory leak for
every elpa_allocate()/elpa_deallocate() cycle.

The were a couple of places where a load of a stack variable was too
wide. Detected with the

  -fsanitize=address

flag of GCC, that we should probably incorporate into our CI tests.

Anything if it makes Andreas happy :)

The timer object was not properly removed when elpa_destroy() was called
on an ELPA instance, leading to a memory leak

Previously you could set up ELPA with nev > na and force a crash.

even if only part of eigenvectors are calculated, all eigenvalues should
be checked

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.