Rename `set` to `parse` for flags.
A few minor changes to the optimizations.

Get rid of unused before/after arrays.
When forcing nodes, return a reference to the underlying array.
Update Black-Scholes benchmark to be slightly more realistic
(different maturity, rate and volatility values for each "stock")
Backout HasStrictTraits change.
Backout changes from pretty print branch.
add Alternating Least Squares on Implicit Feedback method
add streaming kmeans application
fix implicit feedback als
add pca
Merge pull request #127 from spartan-array/flag-names

Rename `set` to `parse` for flags.
Merge pull request #129 from spartan-array/update-optimizations

A few minor changes to the optimizations.
fix operator so it won't produce opposite result when we deal with distarray and expr
Merge pull request #133 from EasonLiao/fix_operator

fix operator
fix a small bug in rpc
Merge branch 'master' of github.com:spartan-array/spartan into fix_operator
Merge pull request #134 from EasonLiao/fix_operator

fix repository
fix lda model to normalize the topic term distribution
Merge pull request #131 from MaggieQi/master

add Alternating Least Squares on Implicit Feedback method
Merge pull request #130 from EasonLiao/pca

add pca
Prettier string representations for most nodes.

The default debug string is useful for... debugging.

It's a little too much information for most purposes.  Change
the default representation to be a bit prettier.
Add missing method.