Resolves #14. Unlike all controls, WebView has 'fn did_load(&self,...)' with self as non-mutable

src/webview/mod.rs

@@ -198,7 +198,7 @@ impl<T> WebView<T> where T: WebViewDelegate + 'static {
     /// Initializes a new WebView with a given `WebViewDelegate`. This enables you to respond to events
     /// and customize the view as a module, similar to class-based systems.
     pub fn with(config: WebViewConfig, delegate: T) -> WebView<T> {
-        let delegate = Box::new(delegate);
+        let mut delegate = Box::new(delegate);
 
         let objc_delegate = unsafe {
             let objc_delegate: id = msg_send![register_webview_delegate_class::<T>(), new];

src/webview/traits.rs

@@ -11,7 +11,7 @@ pub trait WebViewDelegate {
     /// Called when the View is ready to work with. You're passed a `ViewHandle` - this is safe to
     /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
     /// main thread!
-    fn did_load(&self, _webview: WebView) {}
+    fn did_load(&mut self, _webview: WebView) {}
 
     /// Called when this is about to be added to the view heirarchy.
     fn will_appear(&self) {}