Add support for tabularx environments

[Delivers #62651528]
Add support for UTF-8 in title, etc., & custom chaptername

[Delivers #62519814]
Issue pull request for branch utf-8-62519814

[Delivers #62519814](https://www.pivotaltracker.com/story/show/62519814)
[Delivers #62651528](https://www.pivotaltracker.com/story/show/62651528)
Merge pull request #89 from softcover/utf-8-62519814

Utf 8 62519814