add newline feature to the text node, add about window with credits, add about menu with submenus

src/node_scroll.h

@@ -4,11 +4,12 @@
 class NodeScroll : public NodeBorder
 {
     bool m_dragging = false;
-    glm::vec2 m_drag_start;
-    glm::vec2 m_offset_start;
-    glm::vec2 m_offset;
-    glm::vec2 m_mask{ 0, 1 };
+    glm::vec2 m_drag_start = glm::vec2(0);
+    glm::vec2 m_offset_start = glm::vec2(0);
+    glm::vec2 m_offset = glm::vec2(0);
+    glm::vec2 m_mask = glm::vec2(1, 0);
 public:
+    NodeScroll();
     virtual Node* clone_instantiate() const override;
     virtual kEventResult handle_event(Event* e) override;
     void fix_scroll();