Add a WinClose hook

README.asciidoc

@@ -529,6 +529,7 @@ existing hooks are:
  * +InsertMove+: The cursor moved (without inserting) in insert mode, the key
        that triggered the move is used for filtering
  * +WinCreate+: A window was created, the filtering text is the buffer name
+ * +WinClose+: A window was detroyed, the filtering text is the buffer name
  * +WinDisplay+: A window was bound a client, the filtering text is the buffer
        name
  * +WinSetOption+: An option was set in a window context, the filtering text

src/window.cc

@@ -36,6 +36,8 @@ Window::Window(Buffer& buffer)
 
 Window::~Window()
 {
+    Context hook_context{*this};
+    m_hooks.run_hook("WinClose", buffer().name(), hook_context);
     m_options.unregister_watcher(*this);
 }