Merge pull request #1 from pchiusano/master

Stack-safe versions of BitVector functions and tests
Doc improvements
Doc improvements
Add grouped method to BitVector
BitVector#grouped should return a Stream
Scaladoc source links
New ByteVector implementation using balanced trees
Merge pull request #2 from scodec/topic/bytevector-squashed

New ByteVector implementation
added headOption, init, last, lastOption, nonEmpty to ByteVector