* Allow underscores in the link type name
* Add some tests for include anchors
* Include parts of Rust files and hide the rest
Fixes#618.
* Increase min supported Rust version to 1.35
* Add a test for a behavior of rustdoc_include I want to depend on
At first I thought this was a bug, but then I looked at some use cases
we have in TRPL and decided this was a feature that I'd like to use.
Carol (Nichols || Goulding)