Various window code related fixes and documentation changes.

* dispnew.c (change_frame_size_1): Add new_lines instead of
new_height, the latter may be still zero if passed as such.
* window.c (Fwindow_pixel_height): Mention bottom divider in
doc-string.
* window.el (window-min-height, window-min-width): Rewrite
doc-strings.
(window-body-size): Add PIXELWISE argument to make it consistent
with its callees.
* display.texi (Window Dividers): New section.
* frames.texi (Layout Parameters): Add right-divider-width and
bottom-divider-width.
* windows.texi (Window Sizes): Redraw schematic and rewrite its
description.  Rewrite descriptions of `window-total-height',
`window-total-width', `window-total-size', `window-body-height',
`window-body-width' and `window-size-fixed'.  Add descriptions
for `window-pixel-height', `window-pixel-width',
`window-min-height' and `window-min-width'.  Remove description
of `window-size-fixed-p' moving part of it to that of
`window-size-fixed'.
(Resizing Windows): Mention dividers when talking about minimum
sizes.
lisp/frameset.el (frameset--initial-params): Filter out null entries.
* etc/NEWS: Fix paren typo from earlier change
(eww-textarea-map): [tab] doesn't work on tty.


Reported by Mario Lang.

* net/shr.el (shr-map): Ditto.
Recognize dash shell

* lisp/files.el (interpreter-mode-alist):
* lisp/progmodes/sh-script.el (sh-ancestor-alist): Add dash.
* lisp/progmodes/sh-script.el: Fix whitespace in previous change.
Fix ChangeLog bug# typo
* configure.ac: Tweak the "unported" error message.
"Has not been ported to" usually isn't quite correct these days.
Eg it could be an old platform that we dropped support for.
Tweak previous tweak
lisp/gnus/gnus-group.el (gnus-group-make-group): Clarify prompt
* etc/tutorials/TUTORIAL: Mention electric behavior of RET.

Note that I had to change "\" to `\', because otherwise Emacs thought
that everything after that point was inside a string and so did not
indent anything.

So translators should check for anything similar in their translated
versions.
* lisp/emacs-lisp/shadow.el (load-path-shadows-find): Ignore dir-locals.
* lisp/mh-e/mh-compat.el (mh-display-completion-list): Replace use of obsolete
argument of display-completion-list.
* doc/lispref/searching.texi (Replacing Match): Remove incorrect return value
* lisp/simple.el (newline): Doc tweak.

* etc/NEWS: Related edit.
Comment
etc/tutorials/TUTORIAL.es: Adapt to change in English language tutorial.
* xterm.c (xim_initialize): Always pass a copy of resource name
to XRegisterIMInstantiateCallback and eassert whether return
value is True.  Passing copy is important because Xlib doesn't
make its own copy and resource name argument usually points to
SSDATA (Vx_resource_name), which may be changed from Lisp.
(xim_close_display): For XUnregisterIMInstantiateCallback,
always eassert return value and pass exactly the same values
as were used for XRegisterIMInstantiateCallback.  Otherwise
XUnregisterIMInstantiateCallback will always fail.  See Xlib
sources to check why if you are interested.
Doc fix.

* doc/lispref/internals.texi (Window Internals): Remove field
  `region_showing'.
* net/tramp.el (tramp-error): VEC-OR-PROC can be nil.
(tramp-action-password): Clear password cache if needed.
(tramp-read-passwd): Do not clear password cache.

* net/tramp-gvfs.el (tramp-gvfs-handler-askpassword): Clear password
cache unless it is the first password request.