Merge branch 'fix_GFS' into development

.gitlab-ci.yml

Dockerfile

Dockerfile_flexpart

README.md

documentation/docs/building.md

documentation/docs/configuration.md

documentation/docs/index.md

documentation/docs/running.md

documentation/docs/troubleshooting.md

documentation/mkdocs.yml

entrypoint.sh

options/COMMAND

src/FLEXPART.f90

src/advance_mod.f90

src/com_mod.f90

src/conv_mod.f90

src/date_mod.f90

src/drydepo_mod.f90

src/getfields_mod.f90

src/initialise_mod.f90