vfs: add "writelines" This patch allows "writelines" to take "mode" and "notindexed" arguments, because subsequent patch for subrepo requires both.

vfs: add "notindexed" argument to invoke "ensuredir" with it in write mode This patch uses "False" as default value of "notindexed" argument, even though "vfs.makedir()" uses "True" for it, because "os.mkdir()" doesn't set "_FILE_ATTRIBUTE_NOT_CONTENT_INDEXED" attribute to newly created directories.