get rid of ``rho`` in sgd documentation - has been replaced by ``l1_ratio``
Cosmit: more idiomatic way of clipping to zero.

The test also runs 300 milliseconds faster on my machine (1.3s instead
of 1.6).
Demystify magic values in NNLS implementation.
BUG: fix replacement for _neg.
Fix random state where appropriate.
Fixx doctest.
DOC: document attributes fitted by DictVectorizer.
COSMIT various typofixes

As suggested by codespell <https://github.com/lucasdemarchi/codespell>

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Merge pull request #1852 from slattarini/typofixes

COSMIT various typofixes