Merge ropp_pp_occ_tool and ropp_pp_invert_tool

[Ian Culverwell]

This discrepancy between the official ROPP trunk and the dmi_trunk needs fixing. It is making it difficult to merge DMI's changes into ROPP (e.g. see https://trac.romsaf.org/ropp/ticket/638#comment:6). It could involve a lot of work in documentation, test suites (auto and test folder), etc, so it deserves its own ticket.

[Ian Culverwell]

At ROPP CG8 on 14/9/2019 I asked Stig to send me some info on the unification of ropp_pp_occ_tool and ropp_pp_invert_tool in the dmi_trunk. Here is his reply.

The work on combining the invert_tool and the occ_tool, is in these three changesets:

Interpolation of lat, lon and azimuth:
https://trac.romsaf.org/ropp/changeset/4607

New interpolation subroutine also needed in ropp_pp/build/Makefile.am:
https://trac.romsaf.org/ropp/changeset/4608

Incorporation of ropp_pp_invert_tool in ropp_pp_occ_tool:
https://trac.romsaf.org/ropp/changeset/4638/ropp_src/branches/dev/Share/dmi_trunk_8.0/ropp_pp/tools/ropp_pp_occ_tool.f90

The last one sound like the one (Ticket #615), but don't let that fool you, the development actually started in 4607.

So, r4607, r4608 and r4638.

[Ian Culverwell]

Ran out of time. High priority for ROPP-11. Shifting ticket to ROPP-11.

[Ian Culverwell]

Changes to ROPP-11 made at r6787, r6788 and r6790.

[Ian Culverwell]

These changes couldn't be reviewed in time for ROPP-11, but they will be part of the unofficial ROPP-11.1 version, to be released early 2022. Shifting milestone accordingly.