Merge pull request #18 from jkff/master

Two bugs fixed in QDigest and better test for it.
minor - line ending change
fixes #19
minor formatting
fix left shift bug that happens if p >= sp
be explicit about order of operations
set the sparse set threshold based on the number of bits used for the dense representation
make threshold final
add basic validation of constructor args
Merge pull request #20 from seancarr/master

fix two small bugs in encodeHash
fixes #21
fix bug in bias calculation
Merge pull request #22 from seancarr/master

bugfix in getBias()
add ability to disable sparse representation and set sort threshold based on the sparse set threshold
refs #21 - a bit hokey but the threshold data just seems flat wrong so I've modified to provide more reasonable results.  very likely requires more detailed analysis
correct formatting
Merge pull request #23 from seancarr/master

add ability to disable sparse representation
add constructor for no-sparse-set use case
Merge pull request #24 from seancarr/master

add constructor for no-sparse-set use case
add javadoc to constructors and decrease visibility of constructors that require knowledge of internal data representations.