The order of the list of IExpressionBinders in ExpressionBuilder.cs is important because the first matching ExpressionBinder is selected. When a custom expression binder is provided in the user's configuration, this should be used in preference to any of the built-in binders. Prior to this fix the NullableExpresisonBinder would indicate a match if the destination type was of type System.Nullable<> Fixes #1879
Also added a unit test to demonstrate the bug.
Correct order of ExpressionBinders bringing CustomProjectionExpressio…
…nBinder to the top. fixes #1879