Scripts and setups to test the smoothing length computation algorithms in 1D, 2D, and 3D.

There are basically two running modes:

1) generate a new IC with randomly sampled particle positions. Then run exaparty on it and write down the output at t=0 as particles-0.vtu. Finally read that file back in using the provided python script compare_results.py, compute the smoothing lengths using python again (but in a somewhat different manner), and compare the results.

Furthermore, there are 2 types of tests you can run:

a)  The "normal" test, following `run.sh`. This will generate a file containing
    uniformly distributed particles, which are then randomly displaced.
b)  The "multiscale" test, following `run_multiscale.sh`. This will also generate
    a setup that encourages multiscale interactions between particles.

2) Provide the script compare_results.py with an already existing exaparty snapshot (particle-X.vtu file). It then computes the smoothing lengths from the given particle positions, and compares them to the smoothing lengths given in the snapshot.