Macro definitions are just their raw source code, and so should be
highlighted where possible. Also, $ident non-terminal substitutions are
special, and so are worth of a little special treatment.
This adds simple syntax highlighting based off libsyntax's lexer to be sure to
stay up to date with rust's grammar. Some of the highlighting is a bit ad-hoc,
but it definitely seems to get the job done!
This currently doesn't highlight rustdoc-rendered function signatures and
structs that are emitted to each page because the colors already signify what's
clickable and I think we'd have to figure out a different scheme before
colorizing them. This does, however, colorize all code examples and source code.
Closes#11393
All items have source links back to their actual code. Source files can be
omitted with the doc(html_no_source) attribute on the crate. Currently there is
no syntax highlighting, but that will come with syntax highlighting with all
other snippets.
Closes#2072
Removes old rustdoc, moves rustdoc_ng into its place instead (plus drops the _ng
suffix). Also shreds all reference to rustdoc_ng from the Makefile rules.
