IMPORTANT: Corrected obs_write.F and other files.

[arango]

This update corrects a CPP logic in obs_write.F and typos in the *_inp.h for the biologial and sediment models.

• obs_write.F: in ​src:ticket:833 several changes were made to include the fields necessary to compute the Desroziers et al. (2005) statistics for the 4D-Var analysis. This logic is still available when the nonlinear model VERIFICATION is activated. Therefore, we need to avoid such computations because of only made sense in a 4D-Var application. Many thanks to Ann Kristin Sperrevik for bringing this problem to my attention.

• Corrected the assignment of nl_tnu4 in sediment_inp.h. Many thanks to Catherine Drinkorn ​reporting this typo.

• Similarly, tl_tnu4 was unassigned in all the biological models *_inp.h