resolve issue #69, enable warnings when running tests; fix warnings
fix nested list eating labeled list term and tests

- fix nested indented list eating sibling labeled list term
- add a dozen more test cases for complex list scenarios
fixes issue #109 attr refs should not be case sensitive

- additionally, strip whitespace around xref labels
cleanups
allow trailing spaces after block image
Document differences from AsciiDoc

Add section that lists cases where Asciidoctor differs from AsciiDoc.
Merge pull request #112 from mojavelinux/patch-1

Document differences from AsciiDoc
Merge pull request #106 from mojavelinux/test-warnings

Resolve issue #69, enable warnings when running tests; fix warnings
Merge pull request #110 from mojavelinux/list-fix-and-tests

Fix nested list eating labeled list term and tests
Merge pull request #111 from mojavelinux/case-insensitive-attr-refs

Fix issue #109, attr refs should not be case sensitive