Set RESTART_CHECKSUMS_REQUIRED to False

[alperaltuntas]

...unless in TEST or DEBUG mode.

@mnlevy1981, @gustavo-marques what do you think?

[mnlevy1981]

Is there a good reason to do this? I could see it being a performance gain, but the checksum would only be computed during init so it would be a one-time benefit rather than speeding up every time step.

[alperaltuntas]

The reason is, when RESTART_CHECKSUMS_REQUIRED is set to True, users encounter an error when they change the PE layout in between continuation runs.

[mnlevy1981]

That makes sense! I'm okay with changing the default, or with updating the documentation [somewhere?] to make sure users know they need to change this variable in user_nl_mom when changing the PE layout.