Water points and the GST propagators

[arango]

Several changes were made to the internal masking arrays and the computation of water points in ​src:ticket:483. The internal masking arrays are set in routine set_masks and the water points counters are computed in routine wpoints. In that ticket, the calls to these routines were moved from initial to main2d/main3d because we need to know the location of the point sources (via analytical expressions) to process internal masking arrays pmask_io, rmask_io, umask_io, and vmask_io.

It turns out that this breaks the logic to the Generalized Stability Theory (GST) propagators. We need to the call towpoints much earlier to allocated the state arrays that we use to communicate with ARPACK/PARPACK libraries. Therefore, the calls to set_masks and wpoints are moved back to initial (including ADM, TLM, and RPM versions).

The solution is to have a call to ana_psource in routine get_idata (and respective ADM, TLM, and RPM versions), so the locations of the point sources is known before set_masks and wpoints are called. Notice that the point sources locations were already processed in routine get_idata but when reading from input NetCDF forcing file. Now, it also processes analytical point sources locations.

Added an MPI exchange to routine scale_omega to we get identical files in different distributed memory partitions. See ​src:ticket:487 for previous change.