add changelog dialog and display_file api (implemented in osx and ios)

src/node_changelog.cpp

@@ -0,0 +1,26 @@
+#include "pch.h"
+#include "log.h"
+#include "node_changelog.h"
+#include "layout.h"
+
+Node* NodeChangelog::clone_instantiate() const
+{
+    return new NodeChangelog();
+}
+
+void NodeChangelog::init()
+{
+    SetPosition(0, 0);
+    SetWidthP(100);
+    SetHeightP(100);
+    SetPositioning(YGPositionTypeAbsolute);
+    m_template = (*m_manager)[const_hash("changelog")]->m_children[0]->clone();
+    add_child(m_template);
+    btn_ok = m_template->find<NodeButton>("btn-ok");
+    btn_ok->on_click = [&](Node*) { destroy(); };
+}
+
+kEventResult NodeChangelog::handle_event(Event* e)
+{
+    return kEventResult::Consumed;
+}