fixed io closing files and stuff

modules/lib/io.lua

@@ -6,9 +6,12 @@ function io.open(n,m)
  local h=fs.open(n,m)
  if h and m:sub(1,1) == "w" then
   bt=buffer.ucreate()
-  function bt.write(d)
+  function bt.write(_,d)
    return fs.write(h,d)
   end
+  function bt.close()
+   return fs.close(h)
+  end
   return bt
  elseif h and m:sub(1,1) == "r" then
   bt = buffer.ucreate()