refactor layout.h into single file per Node* classes

engine/node_text_input.h

@@ -0,0 +1,14 @@
+#pragma once
+#include "node_border.h"
+#include "node_text.h"
+
+class NodeTextInput : public NodeBorder
+{
+public:
+    NodeText* m_text;
+    std::string m_string;
+    virtual Node* clone_instantiate() const override;
+    virtual void init() override;
+    void init_controls();
+    virtual kEventResult handle_event(Event* e) override;
+};