Fix for language handling

Don't let a "language style" inherit from an automatic style, because
that will "disable" that automatic style. In practice this means always
put language properties an a separate span.
Improve annotations

Allow more content in an annotation. When a FIXME comment is created, an
attempt will be made to render the content in the comment instead of
just skipping it.
Only give warnings about nested text styles when the inner style is a "named" style
Allow dtb:p inside dtb:note when it's only one paragraph

will be rendered as an inline note
Merge branch 'master' of github.com:sbsdev/sbs-pipeline