further cleanup of names: object names to lowercase

da/analysis/expand_fluxes.py

da/analysis/expand_mixingratios.py

da/analysis/siteseries.py

da/analysis/summarize_obs.py

da/baseclasses/dasystem.py

da/baseclasses/obs.py

da/baseclasses/observationoperator.py

da/baseclasses/optimizer.py

da/baseclasses/platform.py

da/baseclasses/statevector.py

da/carbondioxide/obs.py

da/carbondioxide/obspack.py

da/carbondioxide/obspack_geocarbon.py

da/carbondioxide/statevector.py

da/co2gridded/statevector.py

da/examples/das.py

da/examples/dasgridded.py

da/examples/dasjet.py

da/test/test_optimizer.py

da/tm5/observationoperator.py