wip
ENH prettier output from NMF example

Better stopword and noise filtering, increased n_samples to 2000
since the recent optimizations to tf-idf and NMF allow this.

Also some micro-optimizations to NMF itself.
[DOC] Typo fixes in documentation for Novelty and Outlier Detection
Merge pull request #2412 from rolisz/patch-2

[DOC] Typo fixes in documentation for Novelty and Outlier Detection
FIX failing test in NMF due to negative zeros
BUG: remove remaining utf-8 characters in docstrings.
ENH : add score to PCA from ProbabilisticPCA
API : deprecating ProbabilisticPCA
misc
typo
ENH : make PCA scoring work with n_features is big. Avoid covariance computation in PCA.fit
DOC : remove reference to ProbabilisticPCA in doc
update what's new
FIX : do not store precision_ attribute in score method
ENH : add get_precision method with matrix inversion lemma  to PCA for faster scoring
ENH : add tests for get_precision in PCA + some fixes for corner cases
ENH : add get_precision method with matrix inverse lemma  to FactorAnalysis + use precision in score
pep8
ENH : add PCA+FA model selection example
pep8 + misc