Update examples for switch to thiserror

To compensate for the removal of `failure`'s application friendly
`failure::Error` trait, this `anyhow` crate has been added as a
dev-dependency for the examples, but is by no means a necessity for
other crates downstream of CPAL.

Cargo.toml

@@ -17,6 +17,7 @@ lazy_static = "1.3"
 num-traits = "0.2.6"
 
 [dev-dependencies]
+anyhow = "1.0.12"
 hound = "3.4"
 ringbuf = "0.1.6"
 

examples/beep.rs

@@ -1,9 +1,9 @@
+extern crate anyhow;
 extern crate cpal;
-extern crate failure;
 
 use cpal::traits::{DeviceTrait, EventLoopTrait, HostTrait};
 
-fn main() -> Result<(), failure::Error> {
+fn main() -> Result<(), anyhow::Error> {
     let host = cpal::default_host();
     let device = host.default_output_device().expect("failed to find a default output device");
     let format = device.default_output_format()?;

examples/enumerate.rs

@@ -1,9 +1,9 @@
 extern crate cpal;
-extern crate failure;
+extern crate anyhow;
 
 use cpal::traits::{DeviceTrait, HostTrait};
 
-fn main() -> Result<(), failure::Error> {
+fn main() -> Result<(), anyhow::Error> {
     println!("Supported hosts:\n  {:?}", cpal::ALL_HOSTS);
     let available_hosts = cpal::available_hosts();
     println!("Available hosts:\n  {:?}", available_hosts);

examples/feedback.rs

@@ -6,16 +6,16 @@
 //! Uses a delay of `LATENCY_MS` milliseconds in case the default input and output streams are not
 //! precisely synchronised.
 
+extern crate anyhow;
 extern crate cpal;
-extern crate failure;
 extern crate ringbuf;
 
 use cpal::traits::{DeviceTrait, EventLoopTrait, HostTrait};
 use ringbuf::RingBuffer;
 
 const LATENCY_MS: f32 = 150.0;
 
-fn main() -> Result<(), failure::Error> {
+fn main() -> Result<(), anyhow::Error> {
     let host = cpal::default_host();
     let event_loop = host.event_loop();
 

examples/record_wav.rs

@@ -2,13 +2,13 @@
 //!
 //! The input data is recorded to "$CARGO_MANIFEST_DIR/recorded.wav".
 
+extern crate anyhow;
 extern crate cpal;
-extern crate failure;
 extern crate hound;
 
 use cpal::traits::{DeviceTrait, EventLoopTrait, HostTrait};
 
-fn main() -> Result<(), failure::Error> {
+fn main() -> Result<(), anyhow::Error> {
     // Use the default host for working with audio devices.
     let host = cpal::default_host();