Simple RTD server with array function wrapper

This sample was created to provide a simple RTD server to check the behaviour of RTD functions when called from array formulas.

The wrapper function has signature

 public static object RtdArrayTest(string prefix)

and returns a 2x1 array.

The function can be called from Excel as an array formula (with Ctrl+Shift+Enter) using another cell as the "prefix":

 {=RtdArrayTest(D1)}

The implementation of the RTD server is based on the Excel-DNA base class ExcelRtdServer, and just uses a Timer to update the topics.