Remove unused code and clean up warnings.

src/renderer/context_element.rs

@@ -113,8 +113,8 @@ pub trait IntoContextElement: Debug + Walkable /* + CloneIntoBoxedContextElement
 impl<C: ContextElement> IntoContextElement for C {
     fn into_context_element<'a>(
         &'a self,
-        renderer: &DustRenderer,
-        breadcrumbs: &'a Vec<BreadcrumbTreeElement<'a>>,
+        _renderer: &DustRenderer,
+        _breadcrumbs: &'a Vec<BreadcrumbTreeElement<'a>>,
     ) -> Option<IceResult<'a>> {
         Some(IceResult::from_borrowed(self))
     }
@@ -160,8 +160,8 @@ impl<'a> IceResult<'a> {
 impl<'a> IntoContextElement for IceResult<'a> {
     fn into_context_element<'b>(
         &'b self,
-        renderer: &DustRenderer,
-        breadcrumbs: &'b Vec<BreadcrumbTreeElement<'b>>,
+        _renderer: &DustRenderer,
+        _breadcrumbs: &'b Vec<BreadcrumbTreeElement<'b>>,
     ) -> Option<IceResult<'b>> {
         match self {
             IceResult::Owned(rc_ce) => Some(IceResult::from_borrowed(rc_ce.as_ref())),