resolves #470 don't drop whitespace in front of conum on final line (PR #502)
resolves #470 don't drop whitespace in front of conum on final line (PR #502)

- when highlighting with Pygments, don't drop whitespace in front of conum on last line
- move line feed fragment to constant
- don't insert a forced space before conum (since we now preserve the spaces)
- disable Pygments' strip newline behavior (minor optimization only)
asciidoctor/asciidoctor-pdf,Hextremist/asciidoctor-pdf,asciidoctor/asciidoctor-pdf,dsisnero/asciidoctor-pdf,mojavelinux/asciidoctor-pdf,Hextremist/asciidoctor-pdf,dsisnero/asciidoctor-pdf,mojavelinux/asciidoctor-pdf