Fix automatic header id bug
Fix alternate files sort bug
Add follow links keyboard module
Change the  hypertext regex to script-local variable and rename 'create_if_alternates_no_exists' to 'create_if_no_alternates_exists'
Merge pull request #97 from hotleave/master

hypertext: add ability to follow links, also adds keyboard/links submodule.
markdown/headers: support multi-byte ids, improve alternates support.