Make sure warnings aren't triggered by no IDs.

Make sure that other plugins that try to filter `the_title` without passing in two parameters don't interfere with the Subtitles plugin. When `the_title` is filtered, two parameters are needed by Subtitles: the title of the post and the post ID.

If a custom widget or anything else that uses `the_title` does not provide this, then Subtitles will return a PHP warning. So, set the default ID to null if it hasn't been passed to `the_subtitle` and all should be well.

README.md

@@ -230,6 +230,10 @@ An ID isn't necessary for `get_the_subtitle`, but will work for retrieving subti
 
 All versions of _Subtitles_ can be found on the [Releases](https://github.com/philiparthurmoore/Subtitles/releases) page.
 
+### [v1.0.4](https://github.com/philiparthurmoore/Subtitles/releases/tag/v1.0.4) (June 20th, 2014)
+
+- Bug Fix: Make sure that other plugins that try to mess with titles do not cause _Subtitles_ to throw PHP warnings due to the second optional `$id` parameter not being sent to the primary `the_subtitles` method used throughout sites (see [issue](https://github.com/philiparthurmoore/Subtitles/issues/16)).
+
 ### [v1.0.3](https://github.com/philiparthurmoore/Subtitles/releases/tag/v1.0.3) (June 19th, 2014)
 
 - Bug Fix: Ensure that _Subtitles_ works in PHP 5.2.4 environments (see [issue](https://github.com/philiparthurmoore/Subtitles/issues/8)).

public/class-subtitles.php

@@ -507,7 +507,7 @@ public function subtitle_scripts() {
 		 *
 		 * @since 1.0.0
 		 */
-		public function the_subtitle( $title, $id ) {
+		public function the_subtitle( $title, $id = null ) {
 			/**
 			 * Which globals will we need?
 			 *

subtitles.php

@@ -5,7 +5,7 @@
  * Description: Easily add subtitles into your WordPress posts, pages, custom post types, and themes.
  * Author: Philip Arthur Moore
  * Author URI: https://philiparthurmoore.com/
- * Version: 1.0.3
+ * Version: 1.0.4
  * Text Domain: subtitles
  * Domain Path: /languages/
  * License: GNU General Public License v2 or later