Update version number to 2.4.1

plugin/vimwiki.vim

@@ -10,7 +10,7 @@ endif
 let g:loaded_vimwiki = 1
 
 " Set to version number for release, otherwise -1 for dev-branch
-let s:plugin_vers = 2.4
+let s:plugin_vers = "2.4.1"
 
 " Get the directory the script is installed in
 let s:plugin_dir = expand('<sfile>:p:h:h')