Checking Visual Studio projects for consistency

You have a large Visual Studio Solution with dozens of project files in it. How would you verify that all the projects follow certain rules in their property settings, and enforce these rules if a new project is added. For example check that all projects have:

TargetFrameworkVersion = "v4.5"
Platform = "AnyCPU"
WarningLevel = 4
TreatWarningsAsErrors = true
OutputPath = $(SolutionDir)bin
SignAssembly = true
AssemblyName = $(ProjectFolderName)

I know two methods myself that I will add in an answer below, but I was wondering how people go about doing this type of project test, and if there are any good libraries or build tasks available to make this easier.