Reversed search direction, now closes help first

- Reversed the search direction so that if multiple non-normal buffers
should exist together, the topmost would close first instead of the one
with lowest window number.

- Also, switched back to prioritizing help buffers before non-normal
  buffers. Reason is that help files can be easily brough back up again,
  but non-normal buffers could contain program output, logs, and other
  harder to re-create information.