Squashed 'code/markdown2/' content from commit 2bf44c6

git-subtree-dir: code/markdown2
git-subtree-split: 2bf44c6570233da573f8d8dfd43fc5518cabb0b9
Merge commit '282bf06c5604c2c61ceee449310dd375e9a7e8d0' as 'code/markdown2'
Add my fork of markdown2 as subtree to keep all the code in one place.