(tpu-next-file-buffer): Bind starting-buffer with let.
(tpu-load-xkeys): Check value of tpu-xkeys-file.
Make sure to use the "*scratch*" buffer.
(tpu-lm-replace): Changed variable searching-forward
to tpu-searching-forward.
(tpu-substitute): Likewise.
(tpu-toggle-search-direction): Likewise.
(tpu-search-forward, tpu-search-reverse, tpu-set-search): Likewise.
(tpu-search-internal, tpu-adjust-search): Likewise.
