Add temp-buffer-show-specifiers and replace with-output-to-temp-buffer

Add temp-buffer-show-specifiers and replace with-output-to-temp-buffer
with with-help-window.

* window.c (syms_of_window): New variable
temp-buffer-show-specifiers.
(temp_output_buffer_show): Call display-buffer with second
argument set to temp-buffer-show-specifiers and reset the latter
after the call.

* print.c (Fwith_output_to_temp_buffer): In doc-string explain how
to set up temp-buffer-show-specifiers.

* help.el (with-help-window): In doc-string say how to set up
temp-buffer-show-specifiers.

* isearch.el (isearch-help-for-help, isearch-describe-bindings)
(isearch-describe-key, isearch-describe-mode): Replace bindings
for same-window-buffer-names and same-window-regexps by binding
temp-buffer-show-specifiers instead.

* international/mule-diag.el (mule-diag):
* calc/calc-help.el (calc-describe-key, calc-full-help):
* printing.el (pr-show-setup):
* progmodes/python.el (python-describe-symbol):
* textmodes/table.el (*table--cell-describe-mode)
(*table--cell-describe-bindings):
* tutorial.el (tutorial--describe-nonstandard-key)
(tutorial--detailed-help):
* progmodes/vhdl-mode.el (vhdl-doc-variable, vhdl-doc-mode):
* play/yow.el (apropos-zippy): Use with-help-window.

* apropos.el (apropos-command): Remove the message calculation part.
(apropos-print): Use with-help-window

* woman.el (woman-mini-help): Remove the message calculation part.
(woman-display-extended-fonts): Use with-help-window.

* display.texi (Temporary Displays): Describe
temp-buffer-show-specifiers.