Env Variable: AMREX_DEBUG

Introduce control of backtrace handling and exception throwing via
the environment variable `AMREX_DEBUG`.

This is very handly when running CI/CD and IDE workflows to quickly
debug a failing test without overwriting default init parameters.

Docs/sphinx_documentation/source/Debugging.rst

@@ -100,14 +100,16 @@ The following runtime options need to be set in order to prevent AMReX from catc
 
 This default behavior can also be modified by applications, see for example `this custom application initializer <https://github.com/Exawind/amr-wind/blob/84f81a990152f4f748c1ab0fa17c8c663e51df86/amr-wind/main.cpp#L21>`__.
 
-The above default can also be achieve by setting the environment variable ``AMREX_DEBUG``:
+Alternatively, set the environment variable ``AMREX_DEBUG`` to change the defaults in the same way:
 
 .. highlight:: console
 
 ::
 
     export AMREX_DEBUG=1
 
+Note that input and command line arguments always have precendence over environment variables.
+
 
 .. _sec:gpu:debugging: