resolves #785 print runtime environment in version output
Merge pull request #786 from mojavelinux/issue-785

resolves #785 print runtime environment in version output
resolves #768 emit warning if part is invalid

- warn if part has intro content that doesn't have partintro style
- warn if part has no sections
- cleanup invalid multipart book examples in test suite
resolves #768 automatically wrap part intro content in partintro block