add option to define opening and closing of org export letter

lisp/my/my-org-article.el

@@ -568,6 +568,7 @@ IMPORTANT en version must be defined")
   "[paper=a4,fontsize=11pt,DIV=12,BCOR=10mm,headsepline,<<documentclass>>,captions=tableheading,version=first,bibliography=totoc,dvipsnames]"
   "The default LaTeX class options.
 
+Replaces <<...>> with values defined in
 `my-org-article-latex-lang-template-plist'"
   :group 'my-org-export-article
   :type '(string :tag "LaTeX class"))
@@ -2084,6 +2085,7 @@ IMPORTANT en version must be defined")
 
 "
   "Preamble options.
+Text like <<...>>> will be replaced according to
 `my-org-article-latex-lang-template-plist'"
   :group 'my-org-export-article)
 

lisp/my/my-org-letter.el

@@ -48,7 +48,9 @@
 (defvar my-org-letter-latex-default-class-options)
 (defvar my-org-letter-latex-default-header)
 (defvar my-org-letter-latex-default-header-extra)
+(defvar my-org-letter-latex-opening-format)
 (defvar my-org-letter-latex-opening)
+(defvar my-org-letter-latex-closing-format)
 (defvar my-org-letter-latex-closing)
 (defvar my-org-letter-latex-subject)
 (defvar my-org-letter-latex-subject-extra)
@@ -103,7 +105,9 @@
     (:latex-header "LATEX_HEADER" nil my-org-letter-latex-default-header newline)
     (:latex-header-extra "LATEX_HEADER_EXTRA" nil my-org-letter-latex-default-header-extra newline)
     (:latex-compiler "LATEX_COMPILER" nil my-org-letter-latex-compiler)
+    (:letter-closing-format "CLOSING_FORMAT" nil my-org-letter-latex-closing-format newline)
     (:letter-closing "CLOSING" nil my-org-letter-latex-closing newline)
+    (:letter-opening-format "OPENING_FORMAT" nil my-org-letter-latex-opening-format newline)
     (:letter-opening "OPENING" nil my-org-letter-latex-opening newline)
     (:letter-subject "SUBJECT" nil my-org-letter-latex-subject newline)
     (:letter-subject-extra "SUBJECT_EXTRA" nil my-org-letter-latex-subject-extra newline)
@@ -244,7 +248,7 @@
 
 ;;;; Document
 
-(defcustom my-org-letter-latex-opening
+(defcustom my-org-letter-latex-opening-format
   "\\firsthead{
   \\begin{flushright}\\textsf{\\begin{tabular}{l}
   \\fromassociation \\\\ \\usekomavar{fromname} \\\\ \\fromstreet \\\\
@@ -262,13 +266,23 @@
 
 \\setkomavar{subject}{\\subject \\\\ {\\normalfont \\subjectextra}}
 
-\\opening{Sehr geehrter \\toname,}"
-  "Letter opening."
+\\opening{<<opening>>}"
+  "Letter opening structure, will replace <<opening>> with `my-org-letter-latex-opening'."
+  :group 'my-org-letter-latex)
+
+(defcustom my-org-letter-latex-opening
+  "Sehr geehrter \\toname,"
+  "Letter opening, see also `my-org-letter-latex-opening-format'."
+  :group 'my-org-letter-latex)
+
+(defcustom my-org-letter-latex-closing-format
+  "\\closing{<<closing>>}"
+  "Letter closing structure, will replace <<closing>> with `my-org-letter-latex-closing'."
   :group 'my-org-letter-latex)
 
 (defcustom my-org-letter-latex-closing
-  "\\closing{Freundliche Grüße,}"
-  "Letter closing."
+  "Freundliche Grüße,"
+  "Letter closing, see also `my-org-letter-latex-closing-format'."
   :group 'my-org-letter-latex)
 
 
@@ -385,9 +399,17 @@
 		   (format "\\setcounter{tocdepth}{%d}\n" depth))
 		 (plist-get info :latex-toc-command))))
      ;; Document's body.
-     (concat (plist-get info :letter-opening) "\n")
+     (concat (string-replace
+              "<<opening>>"
+              (plist-get info :letter-opening)
+              (plist-get info :letter-opening-format))
+             "\n")
      contents
-     (concat (plist-get info :letter-closing) "\n")
+     (concat (string-replace
+              "<<closing>>"
+              (plist-get info :letter-closing)
+              (plist-get info :letter-closing-format))
+             "\n")
      ;; attachments
      (let ((attachments (plist-get info :letter-attachment)))
        (unless (string-equal attachments "")