handle subs correctly in literal & listing blocks
handle subs correctly in literal & listing blocks

gjtorikian/asciidoctor,asciidocfx/asciidoctor,yukisan/asciidoctor,benignbala/asciidoctor,neontapir/asciidoctor,glamouracademy/asciidoctor,cesarmarinhorj/asciidoctor,mjang/mj-asciidoc,asciidocfx/asciidoctor,anthonny/asciidoctor,yukisan/asciidoctor,anthonny/asciidoctor,cuit-zhaxin/asciidoctor,pepijnve/asciidoctor,benignbala/asciidoctor,gjtorikian/asciidoctor,neontapir/asciidoctor,glamouracademy/asciidoctor,cuit-zhaxin/asciidoctor,mjang/mj-asciidoc,pepijnve/asciidoctor