Changes the default value of several MARBL settings parameters, and also
converts some Fortran parameters to MARBL settings parameters. Adds two new
options:

* lp_remin_scalef -- control whether particulate remin is scaled
* lo2_consumption_scalef -- control whether oxygen consumption is scaled

(For the CESM CMIP6 runs, we will scale oxygen consumption in the deep
Pacific.)

Several new diagnostics were added as well.