Resolve #210: InvalidWmpVersionException on start when no WMP installed

This is a partial revert of f8d9b41.

That change introduced reporting errors for custom sound playback, which is done via a Windows Media Player (WMP) dependency. Unfortunatley, it reports errors on startup instead of just when attempting to play a custom sound.

It's better to fail silently to play custom sounds than to show an error message for all users who don't have WMP installed, since use of custom sounds is rare. We'll fix playback of custom sounds as part of #173 by removing the WMP dependency.

Hourglass/Windows/SoundPlayer.cs

@@ -9,7 +9,7 @@ namespace Hourglass.Windows
     using System;
     using System.Windows.Media;
     using System.Windows.Threading;
-    using Hourglass.Managers;
+
     using Hourglass.Timing;
 
     /// <summary>
@@ -58,7 +58,6 @@ public SoundPlayer()
             // File sound player
             this.mediaPlayer = new MediaPlayer();
             this.mediaPlayer.MediaEnded += this.MediaPlayerOnMediaEnded;
-            this.mediaPlayer.MediaFailed += this.MediaPlayerOnMediaFailed;
         }
 
         #endregion
@@ -335,16 +334,6 @@ private void MediaPlayerOnMediaEnded(object sender, EventArgs e)
             }
         }
 
-        /// <summary>
-        /// Invoked when an error is encountered in the <see cref="MediaPlayer"/>.
-        /// </summary>
-        /// <param name="sender">The <see cref="MediaPlayer"/>.</param>
-        /// <param name="e">The event data.</param>
-        private void MediaPlayerOnMediaFailed(object sender, ExceptionEventArgs e)
-        {
-            ErrorManager.Instance.ReportError(e.ErrorException.ToString());
-        }
-
         #endregion
     }
 }