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 Job ID Name Coverage
  Build Docker
passed #655689
build_docker_from_cache

00:00:19

 
  Test
passed #655690
test_python2_with_coverage

00:01:43

80.0%
passed #655691
test_python3

00:01:36