Fixed 2 small errors, connected to the preprocess observations pipeline and the ocean optimization key (follow up from previous update).

Added preprocessing observations pipeline, which reads the obspack files and writes them as pickle files. Small fix in obs_gvp_co2.py for encoding on special characters in dataset_summary. Small bug fix in observationoperator_tm5_cteco2.py in logging message. Small string conversion bug fix in initexit_cteco2 for keeping opts from initial job. Added module load NCO for platform file Aether. Fix for statevectorNHgridded_cteco2.py for optimizing ocean fluxes, which per default should be true, but was now false in case the ocn.optimize key was not present.

Change all instances of .flat to .flatten(), which caused a problem in forward runs.

See merge request !22

Added __init__.py in several directories, to add these directories to the recognized package directories (was needed on Aether)

Updated baseclass observationoperator (random) to account for the option of two observation types (e.g. surface and column)

implemented new CTDAS structure for the CTE-CO2 setup, including XCO2 routines, plus some remaining changes between py2 -> py3