Clear #filetypeplugin for filetype-based ODL (#24)

plug.vim

@@ -125,6 +125,15 @@ function! plug#end()
   endif
 
   filetype off
+  if exists('#filetypeplugin') &&
+        \ !empty(filter(values(g:plugs), 'has_key(v:val, "for")'))
+    unlet! g:did_load_ftplugin
+    augroup filetypeplugin
+      autocmd!
+    augroup END
+    augroup! filetypeplugin
+  endif
+
   " we want to make sure the plugin directories are added to rtp in the same
   " order that they are registered with the Plug command. since the s:add_rtp
   " function uses ^= to add plugin directories to the front of the rtp, we