resolves #365 add indent attribute to verbatim blocks

- indent attribute on block controls leading block indent
- indent attribute on include macro controls leading block indent
- add tests
- change last argument to build_block to options
resolves #367 resolve attribute references in target of include macro
Merge pull request #366 from mojavelinux/reset-block-intent

resolves #365 add indent attribute to verbatim blocks
Merge pull request #368 from mojavelinux/sub-include-target-attributes

resolves #367 resolve attribute references in target of include macro
resolves #196 support alternative quote forms

- "air quotes" blockquotes
- markdown-style blockquotes
- quoted paragraph shorthand blockquote
- update asciidoc.conf to comply as best as possible