Add a reference (HStar2) sparse tree impl for testing. (#26)
Add a reference (HStar2) sparse tree impl for testing. (#26)

Add a reference (HStar2) sparse tree impl for testing.
Martin2112/trillian,gtank/trillian,google/trillian,AlCutter/trillian,RJPercival/trillian,Martin2112/trillian,codingllama/trillian,daviddrysdale/trillian,google/trillian,gdbelvin/trillian,gtank/trillian,daviddrysdale/trillian,gdbelvin/trillian,codingllama/trillian,AlCutter/trillian,daviddrysdale/trillian,gdbelvin/trillian,RJPercival/trillian,Martin2112/trillian