Assembly/Conference: add GIS fields (poi + boundaries)

.gitlab-ci.yml

Dockerfile

deployment/postgres/init/init-db.sh

src/.envrc

src/core/admin.py

src/core/locale/de/LC_MESSAGES/django.po

src/core/locale/en/LC_MESSAGES/django.po

src/core/migrations/0099_assembly_location.py

src/core/models/assemblies.py

src/core/models/conference.py

src/hub/settings/base.py

src/hub/settings/default.py