Vendor dependencies for 0.3.0 release

vendor/calloop/examples/high_precision.rs

@@ -0,0 +1,30 @@
+use std::time::{Duration, Instant};
+
+use calloop::{
+    timer::{TimeoutAction, Timer},
+    EventLoop,
+};
+
+fn main() {
+    // As of calloop v0.11 there is no difference between low and high precision event loops.
+    let mut event_loop = EventLoop::try_new().expect("Failed to initialize the event loop!");
+
+    let before = Instant::now();
+
+    event_loop
+        .handle()
+        .insert_source(
+            Timer::from_duration(Duration::from_micros(20)),
+            |_, _, _| TimeoutAction::Drop,
+        )
+        .unwrap();
+
+    event_loop.dispatch(None, &mut ()).unwrap();
+
+    let elapsed = before.elapsed();
+
+    println!(
+        "The event loop slept for {} microseconds.",
+        elapsed.as_micros()
+    );
+}