Implements the new publish and unpublish events in the PublishingStrategy.

Making the PublishStrategy public, so that its possible to subscribe to the events.
Removing the old PublishingEventArgs, which is no longer used.
Correcting a few comments.

src/Umbraco.Core/Models/ContentBase.cs

@@ -31,7 +31,6 @@ namespace Umbraco.Core.Models
             Mandate.ParameterNotNull(contentType, "contentType");
             Mandate.ParameterNotNull(properties, "properties");
 
-            //_parentId = parentId;
             _parentId = new Lazy<int>(() => parentId);
 
             _contentTypeId = int.Parse(contentType.Id.ToString(CultureInfo.InvariantCulture));
@@ -74,7 +73,6 @@ namespace Umbraco.Core.Models
         /// <summary>
         /// Gets or sets the Id of the Parent entity
         /// </summary>
-        /// <remarks>Might not be necessary if handled as a relation?</remarks>
         [DataMember]
         public virtual int ParentId
         {