bug#50143: 28.0.50; Various issues with `tamil-itrans' input method

[Visuwesh]

[ஞாயிறு, மார்ச் 13 2022] Visuwesh wrote:
> [வியாழன், பிப்ரவரி 17 2022] Eli Zaretskii wrote:
> [...]
>
> I finally decided to procrastinate by working on this patch for once,
> please see updated patch below.  I'm not really sure if the commit
> message's format is okay (C-c C-w barfs at me), so I tried to do it
> manually.  Also, I think the NEWS entries can be improved but I'm not
> sure how.
>
> [...]

I forgot to include these two details:

    1. There's still a problem with tamil-itrans docstring.  It
       currently leads the user into thinking that they can input the
       Tamil digits.  The problem is that I am not sure how I can split
       `quail-tamil-itrans-various-signs-and-digits-table' into two
       cleanly.  Ideas are welcome.
   
   2. The problem with the include variable syntax is because `quail-help'
      (which is used eventually by `describe-input-method') calls
      `substitute-command-keys' on the docstring so to get the intended
      behaviour, one has to write \\=\\<VAR> not \\<VAR>.  The logic,
      otherwise, is fine.  Maybe this needs to be documented?  WDYT.