cleanup of obsolete comments and dead code

This removes the App.Renderer.Buffered, which was not improving on the
direct renderer, which has a simpler implementation and was keept for
this regard.

src/layout/Padding.zig

@@ -32,7 +32,6 @@ pub fn Layout(comptime Event: type, comptime Element: type, comptime Renderer: t
         events: Events = undefined,
         config: Config = undefined,
 
-        // TODO: padding (for all 4 directions?)
         const Config = struct {
             padding: ?u16 = undefined,
             left: u16 = 0,