Combine rustdoc, prep.js and extract-tests.js

[brson]

rustdoc needs syntax highlighting and the ability to execute code examples, and it would be nice if all the documentation logic were inside rustdoc (there's a lot of boilerplate in tests.mk to support doc tests).

extract-tests.js we can rewrite in Rust using an integrated driver (instead of using compiletest as we currently do). The parts of prep.js that interpret the little directives embedded in examples can be rewritten in rust. For now, the syntax highlighting scripts can be include!ed in rustdoc and rustdoc can drive the python script. Ultimately, pandoc should handle the syntax highlighting.

[metajack]

nominating feature complete

[graydon]

sub-bug of #5413

[pnkfelix]

extracting tests from api docs is important enough for milestone. accepted for milestone production ready.

[brson]

Syntax highlighting is now provided by pandoc, so we don't need js for it.

[thestinger]

This is still an issue. The pandoc on the doc builder needs to be updated.

[pnkfelix]

Assigning P-low.

[alexcrichton]

Closing, this has been completed.