LUA: add addsubtitle control

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

share/lua/http/requests/README.txt

@@ -24,6 +24,9 @@ status.xml or status.json
 > add <mrl> to playlist:
   ?command=in_enqueue&input=<mrl>
 
+> add subtitle to currently playing file
+  ?command=addsubtitle&val=<path>
+
 > play playlist item <id>. If <id> is omitted, play last active item:
   ?command=pl_play&id=<id>
 

share/lua/intf/modules/httprequests.lua

@@ -88,6 +88,8 @@ processcommands = function ()
 	  vlc.msg.err( "</options>" )
 	  --]]
 	  vlc.playlist.add({{path=stripslashes(input),options=options}})
+	elseif command == "addsubtitle" then
+	  vlc.input.add_subtitle (stripslashes(val))
 	elseif command == "in_enqueue" then
 	  vlc.playlist.enqueue({{path=stripslashes(input),options=options}})
 	elseif command == "pl_play" then