Rename 'ExtensionMethods' to 'TypeSystemExtensions'.

This avoids a naming conflict with other extension method classes in the solution.

ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj

@@ -137,7 +137,7 @@
     <Compile Include="TypeSystem\DefaultSolutionSnapshot.cs" />
     <Compile Include="TypeSystem\DomRegion.cs" />
     <Compile Include="TypeSystem\EntityType.cs" />
-    <Compile Include="TypeSystem\ExtensionMethods.cs" />
+    <Compile Include="TypeSystem\TypeSystemExtensions.cs" />
     <Compile Include="TypeSystem\FullTypeName.cs" />
     <Compile Include="TypeSystem\IAmbience.cs" />
     <Compile Include="TypeSystem\IAssembly.cs" />

ICSharpCode.NRefactory/TypeSystem/TypeSystemExtensions.cs

@@ -28,7 +28,7 @@ namespace ICSharpCode.NRefactory.TypeSystem
 	/// <summary>
 	/// Contains extension methods for the type system.
 	/// </summary>
-	public static class ExtensionMethods
+	public static class TypeSystemExtensions
 	{
 		#region GetAllBaseTypes
 		/// <summary>