Add interface to unify C and Fortran names

This commit does not change the interfaces defined in ELPA_2015.11.001 !
All functionality is available via the interface names and definitions
as in ELPA_2015.11.001

But some new interfaces have been added, in order to unfiy the
references from C and Fortran codes:

- The procedures to create the ELPA (row/column) communicators are now
  available from C _and_ Fortran with the name "get_elpa_communicators".
  The old Fortran name "get_elpa_row_col_comms" and the old C name
  "elpa_get_communicators" are from now on deprecated but still available

- The 1-stage solver routines are available from C _and_ Fortran via
  the names "solve_evp_real_1stage" and "solve_evp_complex_1stage".
  The old Fortran names "solve_evp_real" and "solve_evp_complex" are
  from now on deprecated but still functional.

All documentation (man pages, doxygen, and example test programs) have
been changed accordingly.

This commit implies a change in the API versioning number, but no
changes to codes calling ELPA (if they have been already updated to the
API of ELPA_2015.11.001)
parent b1df09cd