Add tests for std::range and expose via prelude

This adds tests for std::range, and exposes std::range::Range to every
module via the prelude. This removes the need for an explicit import of
`std::range` just to write code such as `1..5`.
14 jobs for master in 12 minutes and 56 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Test
passed #132019989
lint:clippy

00:04:40

passed #132019990
lint:rustfmt

00:01:27

passed #132019991
lint:versions

00:00:56

passed #132019983
test:compiler:linux

00:01:45

passed #132019984
macos
test:compiler:macos

00:01:07

passed #132019985
test:ivm-nightly:linux

00:04:50

passed #132019987
macos
test:ivm-nightly:macos

00:06:04

passed #132019986
test:ivm-stable:linux

00:04:12

passed #132019988
macos
test:ivm-stable:macos

00:05:26

 
  Build
passed #132019992
build:ivm:linux

00:04:52

passed #132019993
macos
build:ivm:macos

00:05:16

 
  Test Runtime
passed #132019994
test:runtime:linux

00:00:58

passed #132019995
macos
test:runtime:macos

00:00:38

 
  External
passed continuous-integration/appveyor/branch