Aggregators compose. This adds the methods.
Fixed bug in QTreeTest
add mailing list
add archive link.
fix mailing list
Added code + test to combine tuple of aggregators into one aggregator.
FlagMonoid
OrValMonoid and AndValMonoid
simpler AndValMonoid
Merge pull request #198 from mikegagnon/flag_monoid

FlagMonoid performs logical OR
stash
ScMapMonoid
avoid instanceOf
refactor
tests for ScMap algebras
change val to def
Merge pull request #196 from twitter/feature/mailing_list

Add Community Section to README.md
Merge pull request #195 from stephanh/patch-1

Fixed bug in QTreeTest
Merge pull request #197 from stephanh/generated-tuple-aggregators

Added code to combine tuple of aggregators into one aggregator.
Merge pull request #199 from mikegagnon/map_monoid

scala.collection.Map algebras