bug#20486: 24.4; ispell.el new LocalWords together with existing

[Kevin Ryde]

When ispell.el "A" adds a new LocalWords line it always puts it at the
end of the file.  It'd be good to put it with existing such lines if
there are some.

This helps if LocalWords are deliberately not at the very end of file,
eg. before a special footer.  foo.el below shows this in an elisp file

    M-x find-file  foo.el
    M-x eval-buffer
    =>
    alas new LocalWords line after the ";;; foo.el ends here" footer

I hoped LocalWords with the existing ones would avoid upsetting the
footer bit.

I get some joy from the diff below.  The existing (open-line) and
(newline) are unchanged for the case no existing LocalWords so add at
end of file.  I'm fairly confident of my (insert "\n") when adding after
an existing LocalWords line, since since don't want `newline' to
auto-fill or otherwise mangle that line.  (But I'm ready to be persuaded
if there's some left indent or similar to apply which I don't know.)

2015-05-02  Kevin Ryde  <user42_kevin@yahoo.com.au>

        * textmodes/ispell.el (ispell-add-per-file-word-list): Add new
        LocalWords line just after existing such lines.  Good to keep words
        together or if deliberately placed somewhere special.

foo.el
Description: application/emacs-lisp

ispell.el.diff
Description: Text Data

In GNU Emacs 24.4.1 (i586-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2015-03-08 on binet, modified by Debian
Configured using:
 `configure --build i586-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 
--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --build i586-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes
 
--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --with-x=yes --with-x-toolkit=lucid --with-toolkit-scroll-bars
 --without-gconf --without-gsettings 'CFLAGS=-g -O2
 -fstack-protector-strong -Wformat -Werror=format-security -Wall'
 CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-z,relro'