Hydro tests

Tests on hydrodynamic methods

advect2u

Tests advection methods

test_double_mach

2D double mach reflection problem

From broken link <https://ww.astro.virginia.edu/VITA/ATHENA/dmr.html>_

test_implosion

Runs a 2D implosion problem. Tests Initial:<field>:value. Test outputs density image file and mesh image file.

test_implosion-code

Runs a 2D implosion problem. Tests Initial:code.

test_kelvin_helmholtz

Sample Kelvin Helmholtz instability test. Test outputs density image file and mesh image file.

test_turbulence3d

Tests turbulence method