Merge branch 'feature/fs1467-fix-gmres-and-minres-for-complex'

Fix broken handling of complex problems in MINRES and GMRes. With these
patches, both solvers now support complex matrices as well as complex
right-hand sides. Due to a couple of bugs, the convergence rate of
complex problems was off even before the current breakage.

* feature/fs1467-fix-gmres-and-minres-for-complex:
  [Documentation] Add file comment and formatting hints to complexdata.hh
  [complexmatrixtest] Rename assemble_random_matrix_vectors.hh -> complexdata.hh
  [CMake] Properly exclude header from headercheck.
  [Buildsystem] Ignore helper header for complexmatrixtest
  [Bugfix] GMRes now needs enable_if, so include common/typetraits.hh
  [Tests] Move tests to exercise MINRES and GMRes on complex matrices into separate executable
  [Cleanup][Tests] Rearranged the automatically parsed code for the assembling of the random matrices and random vectors in assemble_random_matrix_vectors.hh for better readability
  [Autotools] added new header file in the Makefile.am
  [Tests] added tests using complex nonsingular matrices and complex hermitian matrices to test the MinRes and GMRes solver on purely complex problems
  [Bugfix] Exploit analytical properties in MINRES to avoid special-casing for complex case
  [Bugfix] fixed order of the scalar product when applying the Arnoldi algorithm in GMRes solver, which is important in the complex case
  [Bugfix] implemented complex Givens rotations and fixed MinRes and GMRes for complex valued problems