Add hints about frozen packages to cache:flush command
Precompiled Reflection data is not recreated on flushing the cache (without --force flag). This can be confusing to people updating frozen packages.
The regular flush command should output a list of frozen packages like:
Note: Precompiled reflection data of frozen packages has not been removed. Use typo3.flow3:package:refreeze or specify the --force option of the cache:flush command in order to recreate it. Following packages are frozen: * TYPO3.FLOW3 * TYPO3.Fluid