added xkcd plugin

plugins/xkcd.lua

@@ -0,0 +1,38 @@
+
+function get_xkcd()
+   first_url = http.request("http://xkcd.com/info.0.json")
+   local xcomicinfo = json:decode(first_url)  
+   math.randomseed(os.time())
+   i = math.random(1,xcomicinfo.num) 
+   b = http.request("http://xkcd.com/" .. i .. "/info.0.json")
+   local comicjson = json:decode(b)
+   local link_image = comicjson.img
+   c = http.request("link_image")
+   local title = comicjson.title
+   if link_image:sub(0,2) == '//' then
+      link_image = msg.text:sub(3,-1)
+   end
+   return link_image, title
+end
+
+function send_title(cb_extra, success, result)
+  if success then
+    send_msg(cb_extra[1], cb_extra[2], ok_cb, false)
+  end
+end
+
+function run(msg, matches)
+  local receiver = get_receiver(msg)
+  url, title = get_xkcd()
+  file_path = download_to_file(url)
+  send_photo(receiver, file_path, send_title, {receiver, title})
+  return false
+end
+
+return {
+    description = "send random comic image from xkcd", 
+    usage = "!xkcd",
+    patterns = {"^!xkcd$"}, 
+    run = run 
+}
+