Merge branch 'master' into '119-windows-missing-dlls'

.gitlab-ci.yml

.gitlab/ci/appimage.gitlab-ci.yml

.gitlab/ci/docker.gitlab-ci.yml

CHANGELOG.md

CITATION.cff

Dockerfile

codemeta.json

src/AuxGrid.cc

src/Colourscale.cc

src/Colourscale.h

src/Connection.cc

src/DrawingObjects.h

src/Graph.cc

src/Graph.h

src/HDF5DataBrowser.fl

src/Model.h

src/Myslider.cc

src/PolyGon.cc

src/Quadrilateral.cc

src/Surfaces.cc