Merge branch 'nifty4_add_cython' into 'NIFTy_4'

Add cython to Dockerfile such that pyfftw can be installed

See merge request ift/NIFTy!278
5 jobs for NIFTy_4 in 10 minutes and 49 seconds
latest
Status Job ID Name Coverage
  Build Docker
passed #725019
build_docker_from_scratch

00:08:39

 
  Test
passed #725020
test_python2_with_coverage

00:01:16

80.0%
passed #725021
test_python3

00:01:08

 
  Release
passed #725022
pages

00:00:52

 
  Deploy
passed pages:deploy

00:00:00