bug#22429: Force character to be recognized as LTR inside RTL paragraph

[Andy Moreton <andrewjmoreton@gmail.com>]

On Fri 22 Jan 2016, Eli Zaretskii wrote:

>> Date: Fri, 22 Jan 2016 10:08:06 +0200
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: 22429@debbugs.gnu.org
>> 
>> The correct solution to these problems is to wrap the footnote block
>> in the LRE..PDF or LRI..PDI control characters, so that the footnote
>> is rendered independently of the surrounding bidirectional context.
>
> Actually, LRM should also work, you just need to put it on both sides
> of the footnote, like below:
>
> \begin{hebrew}
>   \pstart
>
> בְּרֵאשִׁ֖ית‎\footnoteA{This is a Hebrew related footnote}‎ בָּרָ֣א אֱלֹהִ֑ים אֵ֥ת הַשָּׁמַ֖יִם וְאֵ֥ת הָאָֽרֶץ׃
>
>   \pend
> \end{hebrew}

While reading this message, I noticed odd behaviour of cursor motion
with <right> and <left> (i.e. right-char and left-char). 

I would expect repeated <right> to move in logical order until the end
of the buffer, but it gets stuck on the newline after "\pstart".
Likewise repeated <left> from the end gets stuck at the newline before
"\pend".

Saving this text in a file "foo.txt" showed the same behaviour (using the
latest emacs-25 branch with "emacs -Q"). Is this expected ?

    AndyM