sPuReMD: do not compute hydrogen bond interactions when there are no valid force field parameters available for the given triplet of atom types. Allow arbitrary numbers of H-bond interactions per atom.

sPuReMD: finalize corrections for pressure calculations. Change output units from GPa to ATMs. Other formatting changes.

PuReMD: backport changes for interaction function calculations. sPuReMD: alignment with PuReMD code.

sPuReMD: add control file parameter to compute atomic system pressure for non-NPT ensembles. Fix issues with isotropic NPT ensemble (incorrect pressure and temperature scalers). Change atomic position remapping behavior to include upper boundaries of the simulation box (shared memory code only). Other code clean-up.

sPuReMD: replace OpenMP critical sections on ext_press with thread-local storage and subsequent reduction (ext_press_local). Other code clean-up.

sPuReMD: corrections to external pressure calculations for NPT-type ensemble simulations (use correct periodic images between reneighboring steps). Other code clean-up.

sPuReMD: fix issue with torsion & conjugation forces being incorrect due to rel_box arithmetic being wrong (incorrect directions for position vectors). Redesign atomic distance and position update functions to support both periodic boundary conditions and non-periodic boundary conditions.  Behavior change: let random_velocity parameter in control file take precedent over specifying a non-zero initial temperature value. Other code clean-up.

sPuReMD: refactoring to better align with PuReMD code. PuReMD: backport sPuReMD changes from validation efforts against Fortran ReaxFF code.