VC6 is not anymore supported as WinMerge compiler. So we can remove those (ugly) hacks for selecting compiler executable name in PreLink.bat.
Another change is not to even try to depend on environment variables to detect if the batch file is run from inside VS or from command prompt. There are different ways to start the batch file and those environment variables are not consistent in them. For example if the releasing script is run from Visual Studio and the script runs another visual studio calling these batch files. Then the environment variables are not set correctly anymore.