To create a new solution folder in VS2013 Express... Open your solution file in a text editor. Add the Project line to the top of the file. If you want to add more than one then you'll have to invent some new GUIDs. Open in VS2013, you can now rename, drag/drop projects into it etc.
Microsoft Visual Studio Solution File, Format Version 12.00
# Visual Studio 2013
VisualStudioVersion = 12.0.21005.1
MinimumVisualStudioVersion = 10.0.40219.1
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "New Folder", "New Folder", " {765E7B51-3482-4523-AE2F-6299401EDD0B}"
EndProject
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