- remove deprecated features
- update ABI and API versioning

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

Likwid

See merge request !16

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

also introducing --with-likwid parameter to the configure script

Can be used to compile with likwid and to enable the likwid to measure
performance of individual compute steps

with AC_COMPILE_IFELSE in the configure.ac script

adding test which splits communicator at the beginning

See merge request elpa/elpa!15

improving forgotten precision macros

See merge request elpa/elpa!14

and runs several elpas (still mpi-based) in parallel. Each elpa
"instance" then splits its communicator to row and column communicator,
as it is always done. This is actually often done in FHI-aims and was
previously leading to issues when using OmniPath. Hopefully was solved
by Intel MPI 2019.3. Keeping the test for future reference.

master_pre_stage (even though it did not solve the issue)

Pkus/devel

See merge request elpa/elpa!13

Fix omp

See merge request !12