Fixed bug in relaxation.cpp regarding permutation symmetry.
Fixed bug in relaxation.cpp regarding permutation symmetry.

In addition, a minor change was made for better performance of
thermal conductivity calculations.

ttadano/ALM,ttadano/alamode,ttadano/alamode,ttadano/ALM,ttadano/alamode,ttadano/alamode,ttadano/ALM,ttadano/ALM