Fix DocTypeMode definition
Update to latest tidy-html5

Use same explicit option values in TidyOptionId. This will improve
compatibility if new options get introduced in tidy-html5.
Update to latest tidy-html5

The latest version of tidy-html5 contains a fix for the problem
that a self-closing div didn't get converted correctly.
Merge pull request #2 from ermshiperete/master

Fix libtidy problems