Now have a nice panel to hold all the UI panels we'll use later.

panel.cpp

@@ -0,0 +1,24 @@
+#include "panel.hpp"
+
+void Panel::resize(int width, int height) {
+  $screen = Screen(width, height);
+}
+
+void Panel::set_renderer(std::function< Element()> render) {
+  $component = Renderer(render);
+}
+
+Screen &Panel::render() {
+  if($must_clear) $screen.Clear();
+  Render($screen, $component->Render());
+  return $screen;
+}
+
+std::wstring Panel::to_string() {
+  std::string screenout = $screen.ToString();
+  return $converter.from_bytes(screenout);
+}
+
+Screen &Panel::screen() {
+  return $screen;
+}