move shaders into .glsl files and add #include feature

src/node_checkbox.cpp

@@ -108,6 +108,14 @@ void NodeCheckBox::set_icon(const std::string& icon_path)
     update_icon();
 }
 
+void NodeCheckBox::set_value(bool checked, bool trigger_event)
+{
+    this->checked = checked; 
+    update_icon();
+    if (trigger_event && on_value_changed)
+        on_value_changed(this, checked);
+}
+
 void NodeCheckBox::update_icon()
 {
     if (m_icon_path.empty())