sPuReMD: backport efforts for SMALL_BOX_SUPPORT from OGOLEM version of code and conditionally compile. Remove unused code. Other code clean-up.

sPuReMD: backport changes for reax_list, struct declaration/definition separation, interaction_function.

PG-PuReMD: fix function pointers for bonded forces. Declare constants appropriately in bonded force computations. Fix sym_index computation for bond list. Other code clean-up.

PG-PuReMD: update build system for LAPACKE. Conditionally include LAPACKE header based on results of compilation.

Merge branch 'full-far-nbrs-list-charge-matrix' of https://gitlab.msu.edu/SParTA/PuReMD into full-far-nbrs-list-charge-matrix.

PG-PuReMD: fix initial list offsets for creating lists. Fix far neighbor and hydrogen bond reallocation checks. Begin refactoring function defitions and declarations to allow compiler to enforce intentions of pointer usage.

PG-PuReMD: fix charge extrapolation. Improve memory management of local portion of charge matrix and reset linear system size for each time step.

PG-PuReMD: add deallocation routines at simulation termination for aiding with validating memory management.

PG-PuReMD: fix CUDA compilation error. Revert library building via libtool due to issues with recognizing custom suffix rules for building CUDA source files and revisit at a later date.

Change MPI build target to use newer MPI-only code by default, and add option to build older MPI code (to be removed in the future).

PG-PuReMD: fix issue with MPI outgoinging buffer size. Refactor MPI communication code for better encapsulation. Continue cleaning up linear solver code.

PG-PuReMD: fix charge matrix allocation issue. Update CUDA code to reflect data structure changes. Begin removing global variables. Seperate struct declarations and definitions to avoid circular data dependencies when refactoring data structures. Small I/O updates.

PG-PuReMD: begin merging preconditioner code from sPuReMD. Make data structures between sPuReMD and PG-PuReMD consistent. Update control file parsing.

PG-PuReMD: merge memory management and step retry logic from MPI+GPU code into MPI-only code. Fix and backport numerous bugs (void pointer arithmetic and dereferences, etc.). Update code to match new data structures. Begin merging changes from OpenMP code (sPuReMD) for preconditioning work.

sPuReMD: make CoM logic consistent with PuReMD. Other build system updates for debugging and newer versions of MPICH.

sPuReMD: add checks on string and file handling. Rewrite PDB writing to be line-by-line. Other refactoring.

sPuReMD: remove debug prints. Default to no good initial guess for out of range values for spline extrapolation.

sPuReMD: move NaN checks on system energy to after logging. This allows better diagnostics for, e.g., the potential logging.

All: fix issue with pi bonds being incorrectly computed in bond orders. Patch originally submitted to LAMMPS mailing list by Tomas Trnka, SCM (refer to Issue #837 on Github).