Return the bool for pressed from the underlying functions and added

comments documenting example use.

src/lib.rs

@@ -716,17 +716,47 @@ impl<'ui> Ui<'ui> {
 
 // Widgets: Radio
 impl<'ui> Ui<'ui> {
+    /// Creates a radio button for selecting an integer value.
+    /// Returns true if pressed.
+    ///
+    /// # Example
+    /// ```rust,no_run
+    /// # use imgui::*;
+    /// # let mut imgui = ImGui::init();
+    /// # let ui = imgui.frame((0, 0), (0, 0), 0.1);
+    /// # let selected_radio_value = 2;
+    /// ui.radio_button(im_str!("Item 1"), &mut selected_radio_value, 1);
+    /// ui.radio_button(im_str!("Item 2"), &mut selected_radio_value, 2);
+    /// ui.radio_button(im_str!("Item 3"), &mut selected_radio_value, 3);
+    /// ```
     pub fn radio_button<'p>(&self,
                             label: &'p ImStr,
                             value: &'p mut i32,
-                            wanted: i32) {
+                            wanted: i32) -> bool {
         unsafe {
-            imgui_sys::igRadioButton(label.as_ptr(), value, wanted);
+            return imgui_sys::igRadioButton(label.as_ptr(), value, wanted);
         }
     }
-    pub fn radio_button_bool<'p>(&self, label: &'p ImStr, value: bool) {
+
+    /// Creates a radio button that shows as selected if the given value is true.
+    /// Returns true if pressed.
+    ///
+    /// # Example
+    /// ```rust,no_run
+    /// # use imgui::*;
+    /// # let mut imgui = ImGui::init();
+    /// # let ui = imgui.frame((0, 0), (0, 0), 0.1);
+    /// # let selected_radio_value = "cats".to_string();
+    /// if ui.radio_button_bool(im_str!("Cats"), state.radio_button_test == "cats") {
+    ///     state.radio_button_test = "cats".to_string();
+    /// }
+    /// if ui.radio_button_bool(im_str!("Dogs"), state.radio_button_test == "dogs") {
+    ///     state.radio_button_test = "dogs".to_string();
+    /// }
+    /// ```
+    pub fn radio_button_bool<'p>(&self, label: &'p ImStr, value: bool) -> bool {
         unsafe {
-            imgui_sys::igRadioButtonBool(label.as_ptr(), value);
+            return imgui_sys::igRadioButtonBool(label.as_ptr(), value);
         }
     }
 }