[Mitgcm-support] Ecco with KPP on

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I have a "working" version of ecco adjoint with kpp on, which ran for
3-days and gave the following gradient checks:

temperature:
       original forward: sumfc =   5617.806407700504    
 pert. original forward: sumfc =   5617.806407723561    
 tangent linear forward: sumfc =  0.0000000000000000E+00
 adoint         forward: sumfc =   5617.806407700504    

 finite diff. sensitivity =   2.3057509679347272E-03
 adjoint      sensitivity =   2.2139507483762699E-03
 linear       sensitivity =   0.0000000000000000E+00
 linear       sensitivity =   0.0000000000000000E+00

taux:
       original forward: sumfc =   5617.806407700504    
 pert. original forward: sumfc =   5617.806490207631    
 tangent linear forward: sumfc =  0.0000000000000000E+00
 adoint         forward: sumfc =   5617.806407700504    

 finite diff. sensitivity =    8250.712744484190    
 adjoint      sensitivity =    5553.394531250000    
 linear       sensitivity =   0.0000000000000000E+00
 linear       sensitivity =   0.0000000000000000E+00

There is no guarantee however that it will not blowup at a later time
though. The idea is to introduce a number (bcepsi, at Dimitri's
suggestion) to bound the values appearing in the denominator from below
so it won't be too small. bcepsi = 10 right now, which is a rather BIG
epsilon, but it can adjusted. CVS tree has been updated with the new kpp
code.