Fix Option::unwrap_err.
Switch chain calls to use Option::chain method
std: modernize net_url

This switches over to using structs and send_maps for
query string parsing.
Add support for bitcount intrinsics
Adds support for the llvm.ctpop, llvm.ctlz and llvm.cttz intrinsics.
bump 0.5 => 0.6, redirect some URLs in docs.
update after/syntax/rust.vim for removal of <-
Fix options passed to gpg in cargo init
Emit a type error for integer literals where the expected type is char

For example, in let x: char = 42; This was an ICE and is now a
proper type error, as per #3477
Remove xfail-fast from trait-composition-trivial
update mandelbrot to pipes, a few other updates
Fix example.
Merge pull request #4271 from ejholmes/ffi-crypto

Fix example in FFI tutorial.
Fix example.
Add Eric Holmes to AUTHORS
Merge pull request #4253 from martindemello/patch-1

Fix options passed to gpg in cargo init
Add Martin DeMello to AUTHORS
Merge pull request #4272 from ejholmes/crates-minimal-example

Fix example in 13.3.
Merge pull request #4251 from erickt/url

std: modernize net_url
Merge pull request #4250 from thestinger/vim

update after/syntax/rust.vim for removal of <-
Merge pull request #4249 from graydon/0.6-bump

bump 0.5 => 0.6, redirect some URLs in docs.