(python-preoutput-skip-next-prompt): New var.

(python-preoutput-skip-next-prompt): New var.
(python-preoutput-continuation): Remove.
(python-preoutput-filter): Simplify correspondingly.
Remove handling of _emacs_ok.  Make sure we skip _emacs_out's prompts.
Loop around to catch embedded _emacs_out output.
(run-python): Send the import&print command on a single line.
(python-send-command): Send command&print on a single line.
(python-send-string): Only add double \n if needed.
(python-send-receive): Loop until the result comes.
(python-mode-running): Defvar it.
(python-setup-brm): Remove unused var `menu'.
Only bind py-mode-map and `features' around brm-init.
(python-calculate-indentation): Remove unused var `point'.
(python-beginning-of-defun): Remove unused var `def-line'.