implement tab close action

src/app/browser.cpp

@@ -41,6 +41,14 @@ Browser::Browser(
         )
     );
 
+    add_action(
+        "tab_close",
+        sigc::mem_fun(
+            * this,
+            & Browser::main_tab_close
+        )
+    );
+
     add_action(
         "debug",
         sigc::mem_fun(
@@ -66,6 +74,11 @@ void Browser::main_tab_append()
     main->tab_append();
 };
 
+void Browser::main_tab_close()
+{
+    main->tab_close();
+};
+
 void Browser::debug()
 {
     gtk_window_set_interactive_debugging(