Show file preview in split pane in fuzzy finder (#534)

* Add preview pane for fuzzy finder

* Fix picker preview lag by caching

* Add picker preview for document symbols

* Cache picker preview per document instead of view

* Use line instead of range for preview doc

* Add picker preview for buffer picker

* Fix render bug and refactor picker

* Refactor picker preview rendering

* Split picker and preview and compose

The current selected item is cloned on every event, which is
undesirable

* Refactor out clones in previewed picker

* Retrieve doc from editor if possible in filepicker

* Disable syntax highlight for picker preview

Files already loaded in memory have syntax highlighting enabled

* Ignore directory symlinks in file picker

* Cleanup unnecessary pubs and derives

* Remove unnecessary highlight from file picker

* Reorganize buffer rendering

* Use normal picker for code actions

* Remove unnecessary generics and trait impls

* Remove prepare_for_render and make render mutable

* Skip picker preview if screen small, less padding

1 files changed, 3 insertions, 3 deletions

diff --git a/helix-term/src/compositor.rs b/helix-term/src/compositor.rs
index 628c4e13..36e54ede 100644
--- a/helix-term/src/compositor.rs
+++ b/helix-term/src/compositor.rs
@@ -46,7 +46,7 @@ pub trait Component: Any + AnyComponent {
     }
 
     /// Render the component onto the provided surface.
-    fn render(&self, area: Rect, frame: &mut Surface, ctx: &mut Context);
+    fn render(&mut self, area: Rect, frame: &mut Surface, ctx: &mut Context);
 
     /// Get cursor position and cursor kind.
     fn cursor(&self, _area: Rect, _ctx: &Editor) -> (Option<Position>, CursorKind) {
@@ -152,8 +152,8 @@ impl Compositor {
 
         let area = *surface.area();
 
-        for layer in &self.layers {
-            layer.render(area, surface, cx)
+        for layer in &mut self.layers {
+            layer.render(area, surface, cx);
         }
 
         let (pos, kind) = self.cursor(area, cx.editor);