1) Implement setHashObjectFn (#62)

* Implement setHashObjectFn

* Fix lint

* Add missing JSDoc (tuyennhv)
(SHA: 35bad6a7368f864156d716b0da17d5c76009262b)

2) getSubTree to support GindexBitstring (#65) (tuyennhv)
(SHA: ca43e1b97e7237d1103741ae1a43b25c9d5d0beb)

3) Release 0.3.7 (#66) (tuyennhv)
(SHA: 720103bae93329d0e3792f3985d62325efca0424)