doc: switch pandoc to html5
doc/rust.HTML: proper version box
doc: tidy and cleanup CSS deps, add tutorial PDF generation
doc: expand tutorial/manual CSS

Cleanup, edit, add some Bootstrap v3.0.0 elements.
rustdoc: nitpicks & cleanup
doc: fix links to comply with the new rustdoc

Closes #9911.
auto merge of #9960 : adridu59/rust/patch-doc-limited, r=alexcrichton

This is #9868 but doesn't move css files to a separate subfolder, which was causing errors on the Rust buildbot.

@alexcrichton