REVIEW-725: use NotationParserBuilder to build error-handling parser
REVIEW-1339: check that the task is complaining about the empty classpath and not some other problem
improved error message
REVIEW-1340: check that the task is complaining about the empty classpath and not some other problem
improved error message
REVIEW-1402: enhance comparison of VersionNumber's

- also looked through usages of VersionNumber.compare() and considered adapting them, but in the end left most of them unchanged
make checkstyle happy
fixed unsafe warning
fixed recent test change
test fixes related to recent changes