* pack small items tightly to fit more items in single chunk, decreasing
the number of hash operations needed
* remove chunk padding - hash algorithm will pad to its own block size
anyway
* express data length in number of items instead of binary bytes at leaf
level (equivalent)
* Added tree hashing algorithm
* Update simple-serialize.md
* add one more ref to tree_hash
* Add the zero-item special case
* list_to_glob to handle empty list
* refactor hash in simple serialize to support arbitrary byte length
* make comment clearer
* add deserialization of hashN
* formatting
* remove specific hash examples