Combine relax_new with relax_old

[19hello]

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[dyzheng]

Hello @19hello , you renamed relax_new/relax.h to relax.h and relax_old/relax_old.h to relax_old.h, I think it is not good names to distinguish these two method, I suggest to rename relax.h to relax_sync.h and relax_old.h to relax_nsync.h , because the main difference between them is synchronization or nsynchronization algorithm in cell-relax calculation.

[19hello]

Hello @19hello , you renamed relax_new/relax.h to relax.h and relax_old/relax_old.h to relax_old.h, I think it is not good names to distinguish these two method, I suggest to rename relax.h to relax_sync.h and relax_old.h to relax_nsync.h , because the main difference between them is synchronization or nsynchronization algorithm in cell-relax calculation.

OK, I will change this tonight.