New timer struct.

Fix frame rate for animated sprites.

src/timer.rs

@@ -1,5 +1,21 @@
-extern crate time;
+use std::time::{Duration, Instant};
 
-pub fn current_time() -> f64 {
-    (time::precise_time_ns() / 1_000_000) as f64
+
+pub struct Timer {
+    time: Instant
+}
+
+impl Timer {
+    pub fn new() -> Timer {
+        Timer {
+            time: Instant::now()
+        }
+    }
+
+    pub fn current_time(&self) -> f64 {
+        let secs = self.time.elapsed().as_secs() as f64;
+        let nanos = self.time.elapsed().subsec_nanos() as f64;
+
+        secs * 1_000.0 + nanos / 1_000_000.0
+    }
 }