1) Expose HashObject interfaces (#59)

* Expose HashObject interfaces

* Fix import issue in tree.test.ts (tuyennhv)
(SHA: 42b42e6591651cfdf4b5e11c8c39832939242b26)

2) Update release.yml (#60) (dapplion)
(SHA: 0dd50ecbca34a990d83432b38e256af28dff4b9c)

3) Release v0.3.5 (#61) (dapplion)
(SHA: d9d35f8fc373a0e76307841c8d27e42de252cee9)