add .refreshFlags() to path/dir/file objects

This will trigger the path refresh callbacks without refreshing the
path's from disk (which takes ages)

lib/nerdtree/path.vim

@@ -544,6 +544,12 @@ function! s:Path.refresh()
     call self.cacheDisplayString()
 endfunction
 
+"FUNCTION: Path.refreshFlags() {{{1
+function! s:Path.refreshFlags()
+    call g:NERDTreeRefreshNotifier.NotifyListeners(self)
+    call self.cacheDisplayString()
+endfunction
+
 "FUNCTION: Path.rename() {{{1
 "
 "Renames this node on the filesystem

lib/nerdtree/tree_dir_node.vim

@@ -439,6 +439,15 @@ function! s:TreeDirNode.refresh()
     endif
 endfunction
 
+"FUNCTION: TreeDirNode.refreshFlags() {{{1
+unlet s:TreeDirNode.refreshFlags
+function! s:TreeDirNode.refreshFlags()
+    call self.path.refreshFlags()
+    for i in self.children
+        call i.refreshFlags()
+    endfor
+endfunction
+
 "FUNCTION: TreeDirNode.reveal(path) {{{1
 "reveal the given path, i.e. cache and open all treenodes needed to display it
 "in the UI

lib/nerdtree/tree_file_node.vim

@@ -372,6 +372,11 @@ function! s:TreeFileNode.refresh()
     call self.path.refresh()
 endfunction
 
+"FUNCTION: TreeFileNode.refreshFlags() {{{1
+function! s:TreeFileNode.refreshFlags()
+    call self.path.refreshFlags()
+endfunction
+
 "FUNCTION: TreeFileNode.rename() {{{1
 "Calls the rename method for this nodes path obj
 function! s:TreeFileNode.rename(newName)