Merge branch 'stateless-is-requires-fit' into 'master'

.gitignore

bob/pipelines/sample_loaders.py

bob/pipelines/tests/test_wrappers.py

bob/pipelines/transformers/__init__.py

bob/pipelines/transformers/function.py

bob/pipelines/utils.py

bob/pipelines/wrappers.py

bob/pipelines/xarray.py

doc/python/pipeline_example_dask.py

doc/python/pipeline_example_dask_sge.py

doc/python/pipeline_example_dask_sge_adaptive.py

doc/sample.rst