elastic tensor errors

Please post to the list, not to me.
Axel maintains pppm/cg, so he can
comment on how difficult it would be to add
the triclinic logic in pppm to ppm/cg.
No one has asked for it before.


pppm/cg can be easily converted in the current (21 Dec 2016) version.

however, from reading the documentation about the various kspace
styles, it should be blatantly obvious, that one can always substitute
pppm for pppm/cg as the latter is simply an optimization of the