Merge branch 'any_all_for_MultiFields' into 'NIFTy_4'

added any() and all() methods to MultiField

See merge request ift/NIFTy!275
3 jobs for fix_refs_in_doc in 2 minutes and 2 seconds
Status Name Job ID Coverage
  Build Docker
passed build_docker_from_cache #655689

00:00:19

 
  Test
passed test_python2_with_coverage #655690

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80.0%
passed test_python3 #655691

00:01:36