Remove conflicting options to update scripts.
Attempt at better error handling with the Windows update script.

* Use `call` to run Ctags because apparently, the way Vim runs background
  Windows scripts means the whole thing will abort if there's an error.
  But here we want to keep going so we get a chance to unlock the tags file
  if possible.
* Add some `ERRORLEVEL` handling code.
* Log more stuff to the log file.