Further amendments of child frame handling and documentation

Further amendments of child frame handling and documentation

* src/frame.c (frame_subsumes_p): New static function
(delete_frame): On ttys refuse to delete a frame that could be
used as surrogate minibuffer frame by surviving frames.
(store_frame_param): Make sure 'minibuffer' parameter does not
reference a deleted window.  If on a tty it references a live
window, make sure its frame has the same root frame as the frame
where the parameter shall be installed.  Also on ttys make sure
that storing the 'parent-frame' parameter does not assign a
surrogate minibuffer frame a different root frame than that of
any of its client frames.  Further on ttys assert that making a
child a new root frame gives it the dimensions of the terminal.
(Fmouse_position_in_root_frame): Don't use XFRAME before
it's clear that FRAME is a frame.
* doc/lispref/elisp.texi (Top): Add menu for Child Frames section.
* doc/lispref/frames.texi (Buffer Parameters): Mention that
value 'child-frame' is not special for 'minibuffer' parameter on
text terminals.
(Visibility of Frames): Fix description of 'iconify-frame'.
(Raising and Lowering): 'minibuffer-auto-raise' is an option.
(Child Frames): Major rewrite using subsections.  Explain new
and deviant features on text terminals - menu bar access,
reparenting, deleting, visibility and minibuffer-only child
frames.
* etc/NEWS: Remove remark that child frames cannot be
arbitrarily reparented on ttys.

(cherry picked from commit 001359ce7650c1ec110b4c38b6f67274d2d29ad1)