Merge branch 'matplotlib_backend' into 'NIFTy_5'

Set matplotlib backend in Dockerfile

See merge request ift/nifty-dev!64

.gitlab-ci.yml

@@ -65,7 +65,6 @@ pages:
   - NIFTy_4
 
 before_script:
-  - export MPLBACKEND="agg"
   - python setup.py install --user -f
   - python3 setup.py install --user -f
 

Dockerfile

@@ -29,6 +29,9 @@ RUN apt-get update && apt-get install -y python-matplotlib python3-matplotlib \
   && python3 -m pip install --upgrade pip && python3 -m pip install jupyter && python -m pip install --upgrade pip && python -m pip install jupyter \
   && rm -rf /var/lib/apt/lists/*
 
+# Set matplotlib backend
+ENV MPLBACKEND agg
+
 # Create user (openmpi does not like to be run as root)
 RUN useradd -ms /bin/bash testinguser
 USER testinguser