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 Name Job ID Coverage
  Build Docker
passed build_docker_from_scratch #725019

00:08:39

 
  Test
passed test_python2_with_coverage #725020

00:01:16

80.0%
passed test_python3 #725021

00:01:08

 
  Release
passed pages #725022

00:00:52

 
  Deploy
passed pages:deploy

00:00:00