Supporting .ltx extension in `TeX-one-master'

[Arash Esbati]

Hi all,

is there a specific reason why we don't support the .ltx extension
inside `TeX-one-master'?  The docstring says:

  Regular expression matching ordinary TeX files.

  You should set this variable to match the name of all files, where
  automatically adding a file variable with the name of the master file
  is a good idea.  When AUCTeX adds the name of the master file as a
  file variable, it does not need to ask next time you edit the file.

.ltx is probably not so popular as .tex, but still, `auto-mode-alist'
has this entry:

  ("\\.ltx\\'" . latex-mode)

and the change is easy:

--8<---------------cut here---------------start------------->8---
diff --git a/tex.el b/tex.el
index da2f91fe..374f202f 100644
--- a/tex.el
+++ b/tex.el
@@ -2296,7 +2296,7 @@ It is suggested that you use the File Variables (see the 
info node
               (member x (quote (t nil shared dwim)))))
   :local t)

-(defcustom TeX-one-master "\\.\\(texi?\\|dtx\\)$"
+(defcustom TeX-one-master "\\.\\(texi?\\|[dl]tx\\)\\'"
   "Regular expression matching ordinary TeX files.

 You should set this variable to match the name of all files, where
--8<---------------cut here---------------end--------------->8---

auctex.texi has to touched as well.

Any comments welcome.

Best, Arash