That is another legacy file no longer included, you can delete it.
you are free to use whatever you like that doesn't offend me if you want to try other things too
but understand you are not working with source code so the package is not intended for "installation" in Visual Studio, it does not need to be compiled or built, it is already compiled. The problems are happening because you are trying to build it and there are a few stray legacy files that it is trying to compile, you can safely delete those files and then it won't cause build errors.
If you really want to work in Visual Studio we recommend using the actual source code which will compile without errors.
http://www.mojoportal.com/getting-the-code-with-tortoisehg.aspx
http://www.mojoportal.com/understanding-the-difference-between-deployment-files-and-source-code.aspx
Hope it helps,
Joe