add better error messages to evaluation visitor

src/AddIns/Debugger/Debugger.AddIn/Debugger.AddIn.addin

@@ -75,11 +75,11 @@
 			          label = "${res:MainWindow.Windows.Debug.DebugExecutable}"
 			          class = "Debugger.AddIn.DebugExecutableMenuCommand"/>
 		</Condition>
-		<MenuItem id="AddExpressionBreakpoint"
+<!--		<MenuItem id="AddExpressionBreakpoint"
 		          insertafter="Toggle Breakpoint"
 		          label = "${res:MainWindow.Windows.Debug.AddExpressionBreakpoint}"
 		          shortcut="Shift|F7"
-		          class = "Debugger.AddIn.AddExpressionBreakpointCommand"/>
+		          class = "Debugger.AddIn.AddExpressionBreakpointCommand"/>-->
 		<MenuItem id="AddWatchExpression"
 		          insertafter="AddExpressionBreakpoint"
 		          label = "${res:MainWindow.Windows.Debug.AddWatchExpression}"

src/AddIns/Debugger/Debugger.AddIn/NRefactory/ExpressionEvaluationVisitor.cs

@@ -300,17 +300,17 @@ namespace Debugger.AddIn
 		
 		Value Visit(TypeResolveResult result)
 		{
-			throw new GetValueException("Types not supported!");
+			throw new GetValueException("Error: Types not supported.");
 		}
 		
 		Value Visit(UnknownMemberResolveResult result)
 		{
-			throw new GetValueException("Member not found!");
+			throw new GetValueException("Error: Member '{0}' not found.", result.MemberName);
 		}
 		
 		Value Visit(UnknownIdentifierResolveResult result)
 		{
-			throw new GetValueException("Identifier not found!");
+			throw new GetValueException("Error: Identifier '{0}' not declared.", result.Identifier);
 		}
 		
 		Value Visit(ArrayAccessResolveResult result)