Merge branch 'core_updates' into 'master'

.gitlab-ci.yml

cache/Dockerfile

cache/configure.sh

cache/mapcache-template.xml

cache/seeder.py

client/Dockerfile

client/html/index.html

config/emg_index-dev.html

config/emg_index-ops.html

config/emg_init-db.sh

config/emg_mapcache-dev.xml

config/emg_mapcache-ops.xml

config/vhr18_index-dev.html

config/vhr18_index-ops.html

config/vhr18_init-db.sh

config/vhr18_mapcache-dev.xml

config/vhr18_mapcache-ops.xml

core/Dockerfile

core/configure.sh

core/registrar.py