Setting a bandwdith of the input matrix via

elpa%set("bandwidth",bw)

tells ELPA 2stage, that matrix is already a banded matrix
with bandwidth bw. Then some compute steps can be skipped

By mistake a procedure has been named
"invert_tridiagonal" but the correct name should be
"invert_triangular"

We decided not to provide this information via the key/value store, but
rather to use the ftimings module for that.

@loh will take care to implement ftimings in the new API
@amarek wants to port the legacy API so that the old global module
  variables still contain valid values

The legacy API is has been (internally) ported to use the new interface.
The intent is that users of the legacy API do not have to change their
codes.

Next step is to completely adapt the .gitlab-ci.yml file

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.

This reverts commit 64ec6ec2.

on misnky

Those are now handled in a C header