Add XmlCore content type

Derived language services can base their content type on this
to pull in some common functionality

Author: mhutch

Editor/XmlContentType.cs

@@ -30,8 +30,13 @@ namespace MonoDevelop.Xml.Editor
 	static class XmlContentType
 	{
 		[Export]
-		[Name (XmlContentTypeNames.Xml)]
+		[Name (XmlContentTypeNames.XmlCore)]
 		[BaseDefinition (StandardContentTypeNames.Code)]
+		public static readonly ContentTypeDefinition XmlCoreContentTypeDefinition = null;
+
+		[Export]
+		[Name (XmlContentTypeNames.Xml)]
+		[BaseDefinition (XmlContentTypeNames.XmlCore)]
 		public static readonly ContentTypeDefinition XmlContentTypeDefinition = null;
 
 		[Export]
@@ -63,6 +68,5 @@ static class XmlContentType
 		[FileExtension (".xsd")]
 		[ContentType (XmlContentTypeNames.Xsd)]
 		internal static FileExtensionToContentTypeDefinition XsdFileExtensionDefinition = null;
-
 	}
 }

Editor/XmlContentTypeNames.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // Copyright (C) Microsoft Corp. All rights reserved.
 // 
 // Permission is hereby granted, free of charge, to any person obtaining
@@ -25,6 +25,12 @@ namespace MonoDevelop.Xml.Editor
 {
 	public static class XmlContentTypeNames
 	{
+		/// <summary>
+		/// Content types that derive from this will inherit some basic functionality
+		/// without lighting up the full XML editor.
+		/// </summary>
+		public const string XmlCore = "xmlcore";
+
 		public const string Xml = "xml";
 		public const string Xslt = "xslt";
 		public const string Xsd = "xsd";