Numerical derivatives for Monin-Obukhov exchange coefficients over land in offline mode

[gmao-rreichle]

Supersedes #918. Adds optional numerical derivatives of Monin-Obukhov exchange coefficients over land in offline mode. Numerical derivatives implemented for Louis and Helfand. Also cleans up and documents surface turbulence code in Catchment GridComp. Numerical derivatives not yet implemented for CatchCN.

New resource parameter MOSFC_EXTRA_DERIVS_LAND replaces incl_Louis_extra_derivs:

    ! MOSFC_EXTRA_DERIVS_LAND: Resource parameter for *offline* (LDAS) mode.
    !
    !  Over *land*, use derivatives of exchange coeffs w.r.t. temp. & humidity.
    !    
    !    0 : none                   Default for Helfand
    !    1 : analytical derivs      Default for Louis;   *not* available for Helfand
    !    2 : numerical  derivs             
    !
    !  Runtimes: Helfand takes ~10 times longer than Louis.  In offline mode, Helfand consumes
    !            about as much CPU as Catchment.  Numerical derivatives triple the runtime of 
    !            the MOSFC scheme.

Successfully 0-diff tested for GEOSldas Intel standard tests at 3b6cced

[biljanaorescanin]

@gmao-rreichle here is testing summary:

1. All GEOSldas regression tests passed.
2. Regression tests for AGCM all failed for change of long name.
   Fail is same for all 1 day AMIP, REPLAY, And no inc REPLAY.
   Here is example from AMIP:
   Comparing NC4 catch_internal_checkpoint using nccmp...
Failure!
Checking for data differences
Checking for metadata differences
DIFFER : VARIABLE : CQ : ATTRIBUTE : long_name : VALUES : "surface_moisture_exchange_coffiecient" <> "surface_moisture_exchange_coefficient"
3. Running regression script was a pass.