group call to apply_fedep together with other routines for external inputs

[JorgSchwinger]

This PR provides a minor improvement of HAMOCC's code logic by grouping together all calls to routines that provide external inputs (dust, N-deposition, riverine input). Results are not bit-for-bit, but the differences are very small (tested with a 200 year NOINYOC_T62_tn21 run).

If there are preferences to wait with this PR until after #269 is merged please indicate this here.

[TomasTorsvik]

@JorgSchwinger - looks fine to me, but I suggest to put it on hold until #269 is merged as we are already in the testing phase for #269.

[jmaerz]

Thanks for taking care of this. Approved. It might be even mergable without conflicts even after #269 .

[TomasTorsvik]

@JorgSchwinger , @jmaerz - I see there is a conflict in mo_hamocc4bcm with this PR. Unless it's important to keep the history of this PR, it may be easier to just create a new branch from current master and re-apply the changes to mo_hamocc4bcm (rather than to merge master into the fix-move_dust branch, resolve the merge conflict there, and then merge fix-move_dust with master).

[JorgSchwinger]

@TomasTorsvik it was only a very small change, so easy to fix. I will merge this PR now.