Surface fluxes adjustment in W4DVAR and W4DPSAS

[arango]

The weak constraint 4DVar data assimilation algorithms (W4DVAR and W4DPSAS) were updated to adjust surface wind stress (ADJUST_WSTRESS) and surface tracer fluxes (ADJUST_STFLUX). The surface adjustment was added earlier to the strong contraint algorithm (IS4DVAR).

Many thanks to Andy Moore for his help in coding and testing these options. We are very happy about our progress in the 4DVar algorithm. There are still more changes comming since we will be adding new capabilies.