Updated DataType factory to use PluginTypeResolver and made the dictionary thread safe.

Updated MacroEngineFactory to use PluginTypeResolver and made it thread safe. Have also
updated it to only create one instance of each IMacroEngine per application which should
increase performance a teeny bit, plus that's how it should be.

src/umbraco.cms/PluginTypeResolverExtensions.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using Umbraco.Core;
 using umbraco.BusinessLogic.Actions;
 using umbraco.businesslogic;
+using umbraco.cms.businesslogic.macro;
 using umbraco.interfaces;
 
 namespace umbraco.cms
@@ -23,5 +24,25 @@ namespace umbraco.cms
 			return resolver.ResolveTypes<IActionHandler>();
 		}
 
+		/// <summary>
+		/// Returns all available IDataType in application
+		/// </summary>
+		/// <param name="resolver"></param>
+		/// <returns></returns>
+		internal static IEnumerable<Type> ResolveDataTypes(this PluginTypeResolver resolver)
+		{
+			return resolver.ResolveTypes<IDataType>();
+		}
+
+		/// <summary>
+		/// Returns all available IDataType in application
+		/// </summary>
+		/// <param name="resolver"></param>
+		/// <returns></returns>
+		internal static IEnumerable<Type> ResolveMacroEngines(this PluginTypeResolver resolver)
+		{
+			return resolver.ResolveTypes<IMacroEngine>();
+		}
+
 	}
 }