It turned out that if a CPU supports SSE the already existing
test for SSE assembly instructions always passes.
However, the compilation of gcc SSE intrinic instructions might
nevertheless fail if gcc is not called with one of the options
"-msse3", "-msse4" , "-msse4.1", "-msse4.2", "-mavx", or "-mavx2"!

Obviously gcc does still not consider SSE as a standard on X86_64
Intel CPUs.

An additional configure test has been introduced, which test for
gcc intrinsic sse instructions. If this test fails, the corresponding
kernels are switched off.

The C++ kernels can be written as C kernels, which simplifies the build
procedure

In order to increase type safty all ELPA2 kernels provide now
an interface. The interfaces for the C/C++ kernels are automatically
generated during the configure step

The utility binary printed the available kernels to stderr.
This is changed. The ELPA library itself still does all prints
on stderr

The test programs are just needed at the build step (make check),
they are useless for users and will not be installed anymore

For the Intel compiler, this was assured with the pragma

  !DEC$ ATTRIBUTES ALIGN: 64:: a

however, other compilers such as gcc of course did not honour this,
which could result in SIGSEGVs in case the variable was not aligned to
32 bytes (by chance!).

This fixes issue #11, thanks to Nico Holmberg for reporting this.

The SSE kernels with blocking of 2,4,6 (real case) and 1,2 (complex)
case are now available by default

Thus the following changes have been done
- introduce new macros in configure.ac and Makefile.am
- renmae the AVX kernels in AVX_AVX2 (they also support AVX2)
- introduce new files with SSE kernel
- introduce new kernel parameters !
- make the SSE kernels callable

The results are identical with previous kernels

- The SSE part will be available in different files.
- Specify whether AVX or AVX2 was used to build

From now on, a Changelog will be updated, before an ELPA release

files

The test programs include the same template now, the
printed messages are thus unified

The configure flag "--enable-shared-memory-only" triggers a build
of ELPA without MPI support:

- all MPI calls are skipped (or overloaded)
- all calls to scalapack functions are replaced by the corresponding
  lapack calls
- all calls to blacs are skipped

Using ELPA without MPI gives the same results as using ELPA with 1 MPI
task!

This version is not yet optimized for performance, here and there some
unecessary copies are done.

Ths version is intended for users, who do not have MPI in their
application but still would like to use ELPA on one compute node

This commit is performance critical and has to be timed carefully.
Thus one can switch back to the old implementation. The new one,
however is more safe and better to debug

This commit might be performance critical, it has to be timed
carefully. Thus one can switch back to the old implementation.
The new one, however, is more safe and better to debug

This change might be performance critical and has to be timed
carefully. Thus it is possible to switch back to the old
implementation. The new one, however, can actually be debbuged