Revert "libstd: Change `Path::new` to `Path::init`."

This reverts commit c54427ddfbbab41a39d14f2b1dc4f080cbc2d41b.

Conflicts:
	src/librustc/driver/driver.rs
	src/librustc/metadata/creader.rs
Rename extra::json::*::init() constructors to *::new()
Rename std::rt::deque::*::init() to *::new()
auto merge of #10796 : kballard/rust/revert-new-naming, r=alexcrichton

Rename the `*::init()` functions back to `*::new()`, since `new` is not
going to become a keyword.