org-irc.el: Add proper export functions for irc

* lisp/org-irc.el (org-irc-export): Add a new function,
  org-irc-export, which properly exports irc links to html and markdown

* lisp/ox-md.el (org-md-link): Remove workaround to get irc links
  working properly in ox-md, and use org-irc's export functions instead

lisp/org-irc.el

@@ -71,7 +71,10 @@
 
 ;; Generic functions/config (extend these for other clients)
 
-(org-link-set-parameters "irc" :follow #'org-irc-visit :store #'org-irc-store-link)
+(org-link-set-parameters "irc"
+			 :follow #'org-irc-visit
+			 :store #'org-irc-store-link
+			 :export #'org-irc-export)
 
 (defun org-irc-visit (link)
   "Parse LINK and dispatch to the correct function based on the client found."
@@ -245,6 +248,16 @@ default."
       ;; no server match, make new connection
       (erc-select :server server :port port))))
 
+(defun org-irc-export (link description format)
+  "Export an IRC link.
+See `org-link-parameters' for details about LINK, DESCRIPTION and
+FORMAT."
+  (let ((desc (or description link)))
+    (pcase format
+      (`html (format "<a href=\"irc:%s\">%s</a>" link desc))
+      (`md (format "[%s](irc:%s)" desc link))
+      (_ nil))))
+
 (provide 'org-irc)
 
 ;; Local variables:

lisp/ox-md.el

@@ -449,7 +449,7 @@ a communication channel."
      (t (let* ((raw-path (org-element-property :path link))
 	       (path
 		(cond
-		 ((member type '("http" "https" "ftp" "mailto" "irc"))
+		 ((member type '("http" "https" "ftp" "mailto"))
 		  (concat type ":" raw-path))
 		 ((string= type "file")
 		  (org-export-file-uri (funcall link-org-files-as-md raw-path)))