GROOVY-6385: groovy.bat: Can't use question mark in script parameters

As suggested by Dominique on the mailing list:

http://groovy.329449.n5.nabble.com/Can-t-use-question-mark-in-script-parameters-td5716658.html
Merge pull request #264 from PascalSchumacher/GROOVY-6385

GROOVY-6385: groovy.bat: Can't use question mark in script parameters