Fix various uses of display-buffer and pop-to-buffer

Fix various uses of display-buffer and pop-to-buffer
to avoid using special-display-* and same-window-* variables.

* lisp/buff-menu.el (Buffer-menu-switch-other-window): Use second arg
of display-buffer.
(Buffer-menu-2-window): Use switch-to-buffer-other-window.

* lisp/replace.el (occur-mode-goto-occurrence)
(occur-mode-display-occurrence) Use second arg of pop-to-buffer
and display-buffer.

* lisp/window.el (display-buffer-alist): Add *Python*.

* lisp/mail/reporter.el (reporter-submit-bug-report): Use second arg of
display-buffer.

* lisp/mail/sendmail.el (sendmail-user-agent-compose): Don't bind the
special-display and same-window variables.
(mail-other-window): Use switch-to-buffer-other-window.
(mail-other-frame): USe switch-to-buffer-other-frame.

* lisp/progmodes/gdb-mi.el (gdb-frame-gdb-buffer): Use
display-buffer-other-frame.
(gdb-display-gdb-buffer): Use pop-to-buffer.

* lisp/progmodes/gud.el (gud-goto-info): Use info-other-window.

* lisp/progmodes/python.el: Don't set same-window-buffer-names.

* lisp/textmodes/bibtex.el (bibtex-search-entry): Use switch-to-buffer.