simplification for spacesaver. before buckets were kept in an option structure called bucketsOption to defer their computation if not needed. upon a more careful look it turns out this is not very often. the idea that buckets does not have to be calculated in case of repeated merges of SSManys was the original main motivation (since this is what a hadoop reducer will do), but the merge depends on min which depends on buckets in almost all situations, so bucketsOption doesn't help us much here. bucketsOption can be hurtful if an SSMany gets serialized and deserialized, since in that case the None gets serialized and buckets has to be recomputed if needed after deserialization.
Merge branch 'release/0.6.0' into develop
a monoid that keeps track of the monoid usage
move to its own package; add mention regarding threading
rename misleading val name
increasing capacity to prevent any practical overflow
no semicolons
add return type to public methods; move totals to long
make threadsafe and optionally not
replace pow(2, i) by bit shifting
address review comments
split classes into their own files
typo
Merge pull request #311 from julienledem/semigroup_stats

a monoid that keeps track of the monoid usage
make distribution immutable now that it contains mutable counters
Merge pull request #313 from julienledem/semigroup_stats

make distribution immutable now that it contains mutable counters
Dynamic Summer Addition
Don't use the built in CMS, mutable local one with synchronized around it for perf
Dynamic summer to support configuration options and tested/benchmarked harder.

Have options to decide what should be a HH, if we should reset our metrics, and what frequency to update the mutable state
Moved some code around, added some comments regarding threading. Cleaned up types