Release 21.06

21.06

• Starting with this release, problem setups written in Fortran are
  no longer supported and will no longer work. Please consult the
  code documentation and example problem setups in Exec/ to understand
  the new problem setup format. If you need help converting a Fortran
  setup to C++, please file an issue. (#1728, #1732)

• Sponge parameters are now only accepted through the inputs file; the
  &sponge namelist in the probin file is no longer read. (#1731)

• Ambient parameters are now only accepted through the inputs file; the
  &ambient namelist in the probin file is no longer read. (#1742)

• The update_sponge_params hook has been removed. (#1716)

• The Fortran problem-specific source file, ext_src_nd.F90, has been
  removed. Problem-specific sources should be implemented in C++ in
  problem_source.H. (#1856)

• Support for the legacy tagging scheme based on probin parameters (denerr,
  tempgrad, etc.) has been removed. These can be replaced with equivalent
  tagging criteria constructed in the inputs file; see the docs or examples
  in Exec/ to see how to use amr.refinement_indicators. (#1834)

• The Fortran set_problem_tags hook has been removed. The C++ replacement
  is problem_tagging() in problem_tagging.H. (#1828)

• The PrescribedGrav functionality has been removed (not replaced with a C++
  implementation). If you want to obtain the same functionality, you can use
  a problem-defined source term (look for problem_source in the documentation)
  and make the appropriate modification for applying it directly to the state
  (e.g. the momentum source term is rho * g). (#1854)

• The custom radiation boundary using lo_bcflag and hi_bcflag coupled with
  an implementation of rbndry has been removed. (#1743)

• We no longer store Reactions_Type in checkpoint files. This means
  that newer versions of Castro will not restart from old version.