Started on a Huffman chapter. Needs sources.
Merge remote-tracking branch 'upstream/master' into huffman
Merge remote-tracking branch 'upstream/master' into huffman
Merge remote-tracking branch 'upstream/master' into huffman
Merge remote-tracking branch 'origin/master' into huffman

Upstream merge
Merge remote-tracking branch 'origin' into huffman
Merge branch 'huffman' of https://github.com/cceckman/pdr into huffman
Merge pull request #60 from cceckman/huffman

Pulling in Charles' Huffman book edits