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- remove deprecated features
- update ABI and API versioning

- updated INSTALL
- change the ELPA vesioning number
- update Changelog and RELEASE_NOTES

Still to do:
- ABI versioning
- API version number
- Release notes
- Changelog
- Issues
- remove deprecated features
- update of API documentation

With this commit ELPA is released in version 2016.05.001.

The branch "bugfixes_current_relaease" will be update to this ref.
A branch ELPA_2016.05 will be created.

With this commit ELPA is released in version 2016.05.001.

The branch "bugfixes_current_relaease" will be update to this ref.
A branch ELPA_2016.05 will be created.

The API versioning number was not updated correctly at the release.
This lead to a wrong soname.

This is fixed now

- provide C interface for ELPA Library

- correct an error in the test case for QR-decomposition

If the QR-decomposition is used wrongly (matrix size is not a
multiple of block size) the the execution will abort, in
order to prevent the wrong results, discussed in a previous commit

Debug messages are now available by setting the environment variable
"ELPA_DEBUG_MESSAGES" to "yes".

We found a bug in the QR-decomposition, which appears for
some matrix sizes and produces wrong results!

If the QR decomposition is switched on, an appropiate warning
is shown.

This bug is still under investigation

As obvious from the previous commits, this release of ELPA
introduces a (optional) QR-decomposition for real valued
matrices. This option can be used at run-time by either setting
an environment variable, or by calling the ELPA-2 solver for
real matrices with an additional flag.

Thus the ABI changed, w.r.t. previous versions.

Furthermore, the build process of ELPA has been made more
consistent. All optimization flags (especially O1, O2 etc.)
have to be set at build time by the user via the CFLAGS, FCFLAGS,
and CXXFLAGS variables. The configure script does not set
automatically the "O-Flags" anymore.

The qr decomposition is now available as a runtime choice.
Some testing has still to be done

Build servers recommend against calling "abort" functions in a
library. Thus, from now on, ELPA  returns a success flag, which
is a change of ABI!

In order to force the user to honour this, the ELPA drivers
are converted to functions, which implies an adaptation and
rebuild of the user code. The driver functions return a
logical "success", which, if it is false, indicates an
error within the library.

It is advised to check catch and check this
return value in the user code, which calls ELPA.

- the ascii files "INSTALL", "README", and "RELEASE_NOTES" are
  updated
- the Makefile.example in the test directory is updated

- the library version number is changed due to change in ABI
- the INSTALL ascii file is updated
- a RELEASE_NOTES file is introduced

- the library version number is changed due to change in ABI
- the INSTALL ascii file is updated
- a RELEASE_NOTES file is introduced