CHANGES

# 19.12

  -- The hydrodynamic source term (the main work of mini-Castro) has been converted
     from a method-of-lines (MOL) integrator to the corner transport upwind (CTU)
     integrator. CTU is the production hydro scheme in Castro. The update for a
     timestep is calculated in a single step using a directionally unsplit scheme,
     rather than the multi-pass, directionally split MOL approach. CTU generally
     takes larger timesteps, at the expense of each update being more expensive.
     This update will change the answers generated by the code, so benchmarks
     should be updated.

# 19.11

   -- OpenACC is now supported as an option for GPU acceleration. If `USE_ACC=TRUE`
      then the Fortran physics routines will be accelerated with OpenACC parallel
      regions. CUDA is still required for the C++ components of the build since
      AMReX will still use it in the backend for its internal operations.

# 19.08

   -- mini-Castro has been substantially updated to look and feel more like
      a mini-app. Inputs files are no longer required, and all configuration
      is set at the command line (the only necessary selection is the number
      of zones per dimension in the simulation). Running the mini-app with
      no command line arguments prints information about how to run it.
      stdout generated during the run has been substantially simplified,
      with a simple diagnostic about the state of the code printed every
      50 timesteps (this frequency is adjustable). Additionally, AMReX has
      been made a git submodule of the code, so it is easy to check out the
      code and its dependency in a single step.

   -- mini-Castro has been relicensed with an MIT license.