integrate USER-MOP package into build and documentat system. apply latest LAMMPS programming style conventions

- remove feature to record the compilation time and date
- remove 'echo -n' based "progress bar"
- update output format for "lmp_machine -h" to be consistent with help output
- move generation of lmpinstalledpkgs.h to be a separate target depending on
  all sources and headers in src folder. this way it is only regenerated
  when files are modified or packages installed

This is to avoid confusion to what LAMMPS considers to be an
integrator like Verlet and RESPA.

This was accomplished with several key changes:
1) Modified fix_shardlow's control flow to match fix_shardlow_kokkos so
that random numbers are pulled fromn the RNGs in exactly the same order.

2) Created random_external_state.h, a simplified version of the Kokkos
random number generator that keeps its state variables external to itself.
Thus it can be used both with and without Kokkos enabled, as long as the
caller stores and passes in the required state variable.

3) Replaced all references to random_mars.h and Kokkos_Random.hpp code in
the fix_shardlow* files with calls to the random_external_state.h code,
guaranteeing that fix_shardlow* is using an identical RNG in all cases.

Result: most (56 of 61) of our internal tests now generate the same results
with kokkos turned on or off.  Four cases still differ due to what appear
to be vectorization caused rounding differences, and the fifth case
appears to be something triggered by the kokkos "atom_style hybrid" code.