failure
This commit removes the usage of the `failure` crate and finishes up the final pieces of the migration to `std::error::Error` and `anyhow`. The `faerie` crate was updated to pull in its migration from `failure` to `anyhow` as well.
extern crate
macro_use
use
This provides assert_le, assert_lt, and so on, which can print the values of the operands.
This is largely the same as #305, but updated for the current tree.
