default to compatibility mode
Allow nonindent space before heading
Revert "default to compatibility mode"

This reverts commit 2a21f4a82e1047d072f345bb6e2fbc65c3913e5a.
allow nonindent space in Setext style headings
fix nonindent space in Setext headers
tweak for OPML
update test suite
Merge branch 'master' of github.com:fletcher/MultiMarkdown-4