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Another blocker for the SuSE build server: Even though the variable is
later not actually used by the function, a recent GCC complains about
the use of an uninitialized value for that variable.

This prevents build on the OBS, as they use compiliation flags that
detect such behaviour.

Error message there:

 ../test/C/driver/legacy_interface/legacy_real_driver_c_version.c:193:12: warning: 'THIS_REAL_ELPA_KERNEL_API' is used uninitialized in this function [-Wuninitialized]
     success = elpa_solve_evp_real_double(na, nev, a, na_rows, ev, z, na_rows, nblk, na_cols, mpi_comm_rows, mpi_comm_cols, my_mpi_comm_world, THIS_REAL_ELPA_KERNEL_API, useQr, useGPU,

 [...]

 I: Program is using uninitialized variables.
    Note the difference between "is used" and "may be used"
 W: elpa uninitialized-variable ../test/C/driver/legacy_interface/legacy_real_driver_c_version.c:193

The public "solve" method has been renamed "eigenvectors" since it
computes the eigenvalues and (at least parts of) the eigenvectors

Another routine "eigenvalues" will just compute the eigenvalues

Still missing is the compatibility layer, currently it only compiles
when configure is called with

  --disable-legacy

Also, a more general solution to parameter passing via environment
variables would be nice.

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

This attempt at a new, more flexible API for ELPA should hopefully
result in less ABI/API breaking changes in the future.

The new API features a generic key/value system for options that can be
extended without changing any exported symbols or function signatures,
so that new, optional features do not influence existing usage of ELPA.

We hope this makes life easier for users of ELPA - at least in the long
run when they migrated to this newest of ABI changes :)

Example usage (explicit documentation to be done in a future commit):

   if (elpa_init(20170403) /= ELPA_OK) then
     error stop "ELPA API version not supported"
   endif

   e = elpa_create(na, nev, na_rows, na_cols, nblk, mpi_comm_world, my_prow, my_pcol, success)

   call e%set("solver", ELPA_SOLVER_2STAGE)
   call e%set("real_kernel", ELPA_2STAGE_REAL_GENERIC)

   call e%solve(a, ev, z, success)

   call e%destroy()

   call elpa_uninit()

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