Add publishing functions for ASCII, Latin-1 and UTF-8

* lisp/org-publish.el (org-publish-org-to-ascii):
(org-publish-org-to-latin1):
(org-publish-org-to-utf8): New functions.

* doc/org.texi (Publishing action): Document the new publishing functions.

Thanks to Matthias Danzl for showing how to do this.

doc/org.texi

@@ -10630,20 +10630,20 @@ possibly transformed in the process.  The default transformation is to export
 Org files as HTML files, and this is done by the function
 @code{org-publish-org-to-html} which calls the HTML exporter (@pxref{HTML
 export}).  But you also can publish your content as PDF files using
-@code{org-publish-org-to-pdf}.  If you want to publish the Org file itself,
-but with @i{archived}, @i{commented}, and @i{tag-excluded} trees removed, use
-@code{org-publish-org-to-org} and set the parameters @code{:plain-source}
-and/or @code{:htmlized-source}.  This will produce @file{file.org} and
-@file{file.org.html} in the publishing
+@code{org-publish-org-to-pdf}, or as @code{ascii}, @code{latin1} or
+@code{utf8} encoded files using the corresponding functions.  If you want to
+publish the Org file itself, but with @i{archived}, @i{commented}, and
+@i{tag-excluded} trees removed, use @code{org-publish-org-to-org} and set the
+parameters @code{:plain-source} and/or @code{:htmlized-source}.  This will
+produce @file{file.org} and @file{file.org.html} in the publishing
 directory@footnote{@file{file-source.org} and @file{file-source.org.html} if
 source and publishing directories are equal.  Note that with this kind of
 setup, you need to add @code{:exclude "-source\\.org"} to the project
 definition in @code{org-publish-project-alist} to avoid that the published
 source files will be considered as new org files the next time the project is
-published.}.  Other files like images only
-need to be copied to the publishing destination, for this you may use
-@code{org-publish-attachment}.  For non-Org files, you always need to
-specify the publishing function:
+published.}.  Other files like images only need to be copied to the
+publishing destination, for this you may use @code{org-publish-attachment}.
+For non-Org files, you always need to specify the publishing function:
 
 @multitable @columnfractions 0.3 0.7
 @item @code{:publishing-function}

lisp/org-publish.el

@@ -574,6 +574,24 @@ See `org-publish-org-to' to the list of arguments."
 See `org-publish-org-to' to the list of arguments."
   (org-publish-org-to "org" plist filename pub-dir))
 
+(defun org-publish-org-to-ascii (plist filename pub-dir)
+  "Publish an org file to ASCII.
+See `org-publish-org-to' to the list of arguments."
+  (org-publish-with-aux-preprocess-maybe
+    (org-publish-org-to "ascii" plist filename pub-dir)))
+
+(defun org-publish-org-to-latin1 (plist filename pub-dir)
+  "Publish an org file to Latin-1.
+See `org-publish-org-to' to the list of arguments."
+  (org-publish-with-aux-preprocess-maybe
+    (org-publish-org-to "latin1" plist filename pub-dir)))
+
+(defun org-publish-org-to-utf8 (plist filename pub-dir)
+  "Publish an org file to UTF-8.
+See `org-publish-org-to' to the list of arguments."
+  (org-publish-with-aux-preprocess-maybe
+    (org-publish-org-to "utf8" plist filename pub-dir)))
+
 (defun org-publish-attachment (plist filename pub-dir)
   "Publish a file with no transformation of any kind.
 See `org-publish-org-to' to the list of arguments."