test and implementation of stable, parallel mean and variance calculations
Neaten up tests
Remove unused code; improve tests
Copy in clojure/contrib/accumulators.clj from https://raw.github.com/clojure/clojure-contrib/master/modules/accumulators/src/main/clojure/clojure/contrib/accumulators.clj
Return variance as floats rather than fractions
Remove dependency on Incanter; embed needed contrib libs; fix tests
Fix dependencies
Strip unnecessary code and dependency
Clean up wreckage of rebase attempt; make it work with 2.0
Rename the contrib.accumulators namespace to cascalog.math.accumulators
Merge pull request #161 from masverba/stable-mean-and-variance

Stable (sample) variance
fixes #194, tricky typo