Fixed some false positives in parameter not used issue.

ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/VariableNotUsedIssues/ParameterNotUsedIssue.cs

@@ -112,6 +112,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 
 				if (methodDeclaration.Body.IsNull)
 					return;
+				if (methodDeclaration.Modifiers.HasFlag (Modifiers.Virtual) || 
+				    methodDeclaration.Modifiers.HasFlag (Modifiers.New) ||
+				    methodDeclaration.Modifiers.HasFlag (Modifiers.Partial))
+					return;
 				var methodResolveResult = ctx.Resolve(methodDeclaration) as MemberResolveResult;
 				if (methodResolveResult == null)
 					return;

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/ParameterNotUsedIssueTests.cs

@@ -178,5 +178,43 @@ class TestClass {
 }";
 			Test<ParameterNotUsedIssue> (input, 1);
 		}
+
+		[Test]
+		public void TestUnusedParameterInVirtualMethod ()
+		{
+			var input = @"
+class TestClass {
+	public virtual void TestMethod (int i)
+	{
+	}
+}";
+			Test<ParameterNotUsedIssue> (input, 0);
+		}
+		
+		[Test]
+		public void TestUnusedParameterInShadowedMethod ()
+		{
+			var input = @"
+class TestClass {
+	public new void TestMethod (int i)
+	{
+	}
+}";
+			Test<ParameterNotUsedIssue> (input, 0);
+		}
+
+		
+		[Test]
+		public void TestUnusedParameterInPartialMethod ()
+		{
+			var input = @"
+partial class TestClass {
+	partial void TestMethod (int i)
+	{
+	}
+}";
+			Test<ParameterNotUsedIssue> (input, 0);
+		}
+
 	}
 }