use separated class files, use hpp header extension, update include model

src/app/browser/header.cpp

@@ -0,0 +1,20 @@
+#include "header.hpp"
+#include "header/menu.hpp"
+#include "header/tab.hpp"
+
+using namespace app::browser;
+
+Header::Header()
+{
+    set_show_title_buttons(
+        SHOW_TITLE_BUTTONS
+    );
+
+    pack_start(
+        * new header::Menu()
+    );
+
+    pack_start(
+        * new header::Tab()
+    );
+}