some byte conversion optimizations
some more minor loop/map optimizations
added a specialized version for norm(DenseVector[Double])
added sbt-idea to plugins
specialize Unit in DenseVector.foreach for better performance
add ZipForeachValues (but not working)
Merge pull request #160 from mengxr/norm

Added a specialized version for norm(DenseVector[Double])
zipValues, which is designed to allow traversing over a pair of
tensor's values.
simple distance implementation based on zipValues
fix to caching for SparseVector
remove natives from default breeze
made a "natives" subproject that will publish
along with breeze.

closes #161
Merge remote-tracking branch 'scalanlp/master'
Merge branch 'dist' of https://github.com/dlwh/breeze into dlwh-dist
Update README.md
fix the return type to Unit in foreach
change distance to squaredDistance
add a specialized implementation for zipValues[DenseVector, DenseVector], which brings
back the performance. The generic one needs multiplication to locate elements.
Merge pull request #162 from mengxr/dist

Add zipValues and squaredDistance for vectors
Merge branch 'master' of https://github.com/scalanlp/breeze into signal