Show tracks + duration of album, playlist, queue

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Fixes #475

src/utils.rs

@@ -0,0 +1,21 @@
+/// Returns a human readable String of a Duration
+///
+/// Example: `3h 12m 53s`
+pub fn format_duration(d: &std::time::Duration) -> String {
+    let mut s = String::new();
+    let mut append_unit = |value, unit| {
+        if value > 0 {
+            s.push_str(&format!("{}{}", value, unit));
+        }
+    };
+
+    let seconds = d.as_secs() % 60;
+    let minutes = (d.as_secs() / 60) % 60;
+    let hours = (d.as_secs() / 60) / 60;
+
+    append_unit(hours, "h ");
+    append_unit(minutes, "m ");
+    append_unit(seconds, "s ");
+
+    s.trim_end().to_string()
+}