merge NIFTy_5

Dockerfile

README.md

docs/source/code.rst

docs/source/conf.py

docs/source/ift.rst

docs/source/index.rst

docs/source/installation.rst

nifty5/__init__.py

nifty5/domains/domain.py

nifty5/fft.py

nifty5/field.py

nifty5/library/adjust_variances.py

nifty5/library/correlated_fields.py

nifty5/library/dynamic_operator.py

nifty5/library/inverse_gamma_operator.py

nifty5/library/light_cone_operator.py

nifty5/library/los_response.py

nifty5/library/smooth_linear_amplitude.py

nifty5/linearization.py

nifty5/logger.py