ENH: renamed fast_svd to randomized_svd + related improvements

benchmarks/bench_plot_svd.py

doc/developers/utilities.rst

doc/whats_new.rst

examples/applications/wikipedia_principal_eigenvector.py

sklearn/decomposition/dict_learning.py

sklearn/decomposition/nmf.py

sklearn/decomposition/pca.py

sklearn/utils/extmath.py

sklearn/utils/tests/test_svd.py