Important: Corrected bug in dateclock.F

[arango]

Corrected a bug in module dateclock.F, routine datevec. The date string failed after 2000-02-28 12:30:00:

        12 2000-02-28 12:30:00.00  1.288030E-06  1.954312E+04  1.954312E+04  1.659839E+17
                      (001,06,01)  1.690266E-06  1.090592E-05  2.506269E-04  5.449963E-02
        13 1999-03-** 12:32:30.00  1.462197E-06  1.954312E+04  1.954312E+04  1.659839E+17
                      (001,06,01)  1.966928E-06  1.180089E-05  2.717118E-04  5.675077E-02
        14 1999-03-** 12:35:00.00  1.632312E-06  1.954312E+04  1.954312E+04  1.659839E+17
                      (001,06,01)  2.265510E-06  1.270431E-05  2.934621E-04  5.892863E-02

It looked like a Y2K bug but it was not a Y2K bug type problem. I have an error at the transition between the end of February (28 or 29) and Mar 1 which is the numerical start of esch uear in the Proleptic Calendaras coded in ROMS. Numerically, it is easier to start each year on March 1 and then adjust for leap year or not.

After the correction, I now get the correct date/clock string:

        12 2000-02-28 00:30:00.00  1.288030E-06  1.954312E+04  1.954312E+04  1.659839E+17
                      (001,06,01)  1.690266E-06  1.090592E-05  2.506269E-04  5.449963E-02
        13 2000-02-28 00:32:30.00  1.462197E-06  1.954312E+04  1.954312E+04  1.659839E+17
                      (001,06,01)  1.966928E-06  1.180089E-05  2.717118E-04  5.675077E-02
        14 2000-02-28 00:35:00.00  1.632312E-06  1.954312E+04  1.954312E+04  1.659839E+17
                      (001,06,01)  2.265510E-06  1.270431E-05  2.934621E-04  5.892863E-02 

Many thanks to Mark Hadfield for ​bringing this to my attention.