Auto-adjust DSL Tools SDK path for V2010
One more kludge on the manifest t4 template to adjust the supported VS version based on which environment the project is compiled. Previous code would setup the manifest so as to allow the built extension to be installable on both VS2010 and 2012, which wouldn't work (e.g., an extension compiled on VS2012 would only work on VS2012 installations, and so on - the extension works only on the same Visual Studio version where it was built on, because of the different assembly references versions)