[IZPACK-1113]

This is to address http://jira.codehaus.org/browse/IZPACK-1113
1. Fix bug where parent packs could not be selected.
2. Display interactive packs selection list like described the Jira issue.
3. Clean up of TreePacksConsolePanel to depend less on internal class state.
    - Makes it easier to understand and test
4. Ensure to handle pack labels the same as GUI and check internationalized strings first.