Add .NET 4.5.1 target framework.

src/Main/Base/Project/Src/Project/TargetFramework.cs

@@ -46,12 +46,17 @@ namespace ICSharpCode.SharpDevelop.Project
 			RequiresAppConfigEntry = true,
 			IsAvailable = DotnetDetection.IsDotnet45Installed
 		};
-//		public readonly static TargetFramework Net45Client = new ClientProfileTargetFramework(Net45) {
-//			BasedOn = Net40Client
-//		};
+		public readonly static TargetFramework Net451 = new TargetFramework("v4.5.1", ".NET Framework 4.5.1") {
+			BasedOn = Net45,
+			MinimumMSBuildVersion = new Version(4, 0),
+			SupportedRuntimeVersion = "v4.0",
+			SupportedSku = ".NETFramework,Version=v4.5.1",
+			RequiresAppConfigEntry = true,
+			IsAvailable = DotnetDetection.IsDotnet451Installed
+		};
 		
 		public readonly static TargetFramework[] TargetFrameworks = {
-			Net45, Net40, Net40Client, Net35, Net35Client, Net30, Net20
+			Net451, Net45, Net40, Net40Client, Net35, Net35Client, Net30, Net20
 		};
 		
 		public readonly static TargetFramework DefaultTargetFramework = Net40Client;

src/Main/Base/Project/Src/Util/DotnetDetection.cs

@@ -6,24 +6,53 @@ using Microsoft.Win32;
 
 namespace ICSharpCode.SharpDevelop
 {
-	public class DotnetDetection
+	public static class DotnetDetection
 	{
+		/// <summary>
+		/// Gets whether .NET 3.5 is installed and has at least SP1.  
+		/// </summary>
 		public static bool IsDotnet35SP1Installed()
 		{
 			using (var key = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\NET Framework Setup\NDP\v3.5")) {
 				return key != null && (key.GetValue("SP") as int?) >= 1;
 			}
 		}
-		
+
+		/// <summary>
+		/// Gets whether any .NET 4.x runtime is installed.
+		/// </summary>		
 		public static bool IsDotnet40Installed()
 		{
 			return true; // required for SD to run
 		}
 		
+		/// <summary>
+		/// Gets whether the .NET 4.5 runtime (or a later version of .NET 4.x) is installed.
+		/// </summary>
 		public static bool IsDotnet45Installed()
 		{
 			Version dotnet45Beta = new Version(4, 0, 30319, 17379);
 			return Environment.Version >= dotnet45Beta;
 		}
+		
+		/// <summary>
+		/// Gets whether the .NET 4.5.1 runtime (or a later version of .NET 4.x) is installed.
+		/// </summary>
+		public static bool IsDotnet451Installed()
+		{
+			// According to: http://blogs.msdn.com/b/astebner/archive/2013/11/11/10466402.aspx
+			// 378675 is .NET 4.5.1 on Win8
+			// 378758 is .NET 4.5.1 on Win7
+			return GetDotnet4Release() >= 378675;
+		}
+		
+		static int? GetDotnet4Release()
+		{
+			using (var key = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full")) {
+				if (key != null)
+					return key.GetValue("Release") as int?;
+			}
+			return null;
+		}
 	}
 }