resolve #212 implement leveloffset feature
extract subtitle from title in docbook backend
Merge pull request #243 from mojavelinux/leveloffset

resolve #212 implement leveloffset feature
resolves #217 don't compact nested documents
resolves #221 honor toc2 attribute
resolves #206 include footnotes block in embedded document
resolve #223 support multiple authors in document header
document multiple authors
Merge pull request #249 from mojavelinux/toc2

resolves #221 honor toc2 attribute
Merge pull request #248 from mojavelinux/compact-once

resolves #217 don't compact nested documents
Merge pull request #247 from mojavelinux/subtitle

extract subtitle from title in docbook backend
resolves #241 negative case for inline ifndef should only affect current line
Merge pull request #250 from mojavelinux/embedded-footnotes

resolves #206 include footnotes block in embedded document
Merge pull request #255 from mojavelinux/multiple-authors

resolve #223 support multiple authors in document header
Merge pull request #256 from mojavelinux/inline-ifndef-fix

resolves #241 negative case for inline ifndef should only affect current...
resolves #260 use code element instead of tt

- perform macro sustitution on email in document header
resolves #262 warn if file in include macro doesn't exist
Merge pull request #261 from mojavelinux/change-tt-to-code

resolves #260 use code element instead of tt
Merge pull request #263 from mojavelinux/warn-on-missing-include

resolves #262 warn if file in include macro doesn't exist