refactor(clippy): adapt to new lints

examples/example.rs

@@ -55,7 +55,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         terminal.draw(|f| {
             let area = f.size();
 
-            let items = Tree::new(app.tree.items.to_vec())
+            let items = Tree::new(app.tree.items.clone())
                 .block(
                     Block::default()
                         .borders(Borders::ALL)

examples/util/event.rs

@@ -44,6 +44,7 @@ impl Events {
             let tx = tx.clone();
             thread::spawn(move || {
                 let stdin = io::stdin();
+                #[allow(clippy::manual_flatten)]
                 for evt in stdin.keys() {
                     if let Ok(key) = evt {
                         if let Err(err) = tx.send(Event::Input(key)) {

examples/util/mod.rs

@@ -37,7 +37,7 @@ impl<'a> StatefulTree<'a> {
             }
             .min(visible.len() - 1)
         });
-        let new_identifier = visible.get(new_index).unwrap().identifier.to_owned();
+        let new_identifier = visible.get(new_index).unwrap().identifier.clone();
         self.state.select(new_identifier);
     }
 

src/flatten.rs

@@ -31,7 +31,7 @@ fn internal<'a>(
 
         result.push(Flattened {
             item,
-            identifier: child_identifier.to_vec(),
+            identifier: child_identifier.clone(),
         });
 
         if opened.contains(&child_identifier) {

src/lib.rs

@@ -34,7 +34,7 @@ impl Default for TreeState {
 
 impl TreeState {
     pub fn selected(&self) -> Vec<usize> {
-        self.selected.to_owned()
+        self.selected.clone()
     }
 
     pub fn select<I>(&mut self, identifier: I)