The Project has moved: https://github.com/nfowler-1/CodedUIMapToolbox
Visual Studio 2015 support has been added January 11th, 2016.
UIMap Toolbox allows you to restructure, split and merge UIMaps created for Microsoft CodedUI tests in Visual Studio 2010, 2012, 2013 and 2015. Developed in C#/.NET 4.0
User Guide including some thoughts on developing maintainable CodedUI tests can be found on the Documentation page.
Integrates into Visual Studio, so it's possible to open UIMap Toolbox directly from the Solution Explorer window:
UIMap Toolbox with two UIMaps opened: