Some improvements to the Cargo compiler file.
Use rustc's errorformat and add option to specify permanent parameters.
Updates based on kballard's feedback.
Added check for absolute file path, removed hard tab, and added documentation for new option.
Fix `Vec::map_in_place` not doing what is written in the comment
libstd: improve os::args() doc
Guide: add a pointer to play.rust-lang.org and explain how to run the code examples.
Fix for issue #17574
Look for standard crates in LIBDIR provided by --libdir option,
not in hardcoded libdir path. If there was no LIBDIR provided
during configuration fallback to hardcoded paths.

Thanks to Jan Niklas Hasse for solution and to Alex Crichton for improvements.

Closes #11671
Conformed the 100 char limit and changed colon to semicolon
libcore: add num::Int::pow() and deprecate num::pow().

Signed-off-by: NODA, Kai <nodakai@gmail.com>
libsyntax: Add `parse_view_item` method to Parser
libsyntax: Add tests for `parse_view_item`
Move trans, back, driver, and back into a new crate, rustc_trans. Reduces memory usage significantly and opens opportunities for more parallel compilation.
make cloned generic over deref... and have its tests actually run
add Cloned iterator adaptor
auto merge of #19031 : nodakai/rust/libcore-pow-and-sq, r=bjz

[breaking-change]

Deprecates `core::num::pow` in favor of `Int::pow`.
Reference: Add missing third dot of range
auto merge of #19070 : nikomatsakis/rust/crates, r=nikomatsakis

Reduces memory usage significantly and opens opportunities for more parallel compilation.

This PR was previously #19002 but I closed it because bors didn't seem to recognize the `r+` annotations there.
auto merge of #19060 : Gankro/rust/super-cloned, r=aturon

Edit: whoops, didn't mean to hit post.

Anyway, this is something I tried to do when I first implemented cloned, but couldn't figure out. Somewhere between then and the PR actually landing, we got Deref of references, so now this works! :tada: 

Also turns out the test for the functionality was never marked as a #[test]. Oops!

Also added a Cloned iterator adaptor. If this isn't desirable, it can be taken out of the PR (seperate commits).