Fix shell output retrieval and comint-prompt-regexp init.

Fix shell output retrieval and comint-prompt-regexp init.
* progmodes/python.el (inferior-python-mode):
(python-shell-make-comint): Fix initialization of
comint-prompt-regexp from copied file local variables.
(python-shell-fetched-lines): Remove var.
(python-shell-output-filter-in-progress): Rename from
python-shell-fetch-lines-in-progress.
(python-shell-output-filter-buffer): Rename from
python-shell-fetch-lines-string.
(python-shell-fetch-lines-filter): Delete function.
(python-shell-output-filter): New function.
(python-shell-send-string-no-output): Use them.