Added detection for drives other than C:\

[DionGR]

The script now iterates through a list of letters in case the user has VS installed in a drive other than C:, to prevent confusion and manual editing of the script. In case no installation was found in the default Program Files (x86) folder, the user is prompted to enter the path manually.

Could save some time for students not familiar with BATCH scripts, and is more precise when giving an error.