Added persistency for the UserInputPanels.
- When hitting the previous button we attempt to save contents of the
  panel into the install data if the saveData() method has been
  implemented for the panel.
- There was inconsistency where some fields like text/radio would be
  saved on previous button, but not password fields.
- This can be useful when a user has to switch back and forth between
  panels and does not want to loose their data.
Added persistency to TargetPanel
Ensure file and directory fields are not expanded when saving without validation. Less confusion for persistency
Properly persist password fields, and no longer remake the userinputpanel everytime it is shown.
Adding new attribute 'updateTrigger' for dynamic variables
- updateTrigger="variable" where variable refers to a variable within idata.
- Indicates that variable should be re-evaluated only when the specified
  update trigger has changed.
Refactoring TreePacksConsolePanel.
- Fixed bug where parent pack could not be selected.
- Now display an interactive packs selection list.
- Remove internal class state, easier to comprehend and test.
Update to handle packs label the same as in GUI.
Internationalize all strings
[IZPACK-1114] Next panel not gathered correctly if they depend on panel conditions
Merge pull request #212 from rkrell/IZPACK-1114

[IZPACK-1114] Next panel not gathered correctly if it depends on panel conditions
Parse pack tags for onSelect and onDeselect tags.
Initial additions of onSelect and deSelect (Conditions not being used
yet).
Starting to strip out the core of PacksModel so that the console can
also use it.

Conflicts:
	izpack-panel/src/main/java/com/izforge/izpack/panels/treepacks/TreePacksConsolePanel.java
Initial refactoring of class variables for PacksModel
More PacksModel Refacotring.
- Use variables rather that 'magic numbers'
- Better integrate setValueAt method from GUI and base PacksModel method
[IZPACK-1114] Next panel not gathered correctly if they depend on panel conditions (post-fix)
Merge pull request #213 from rkrell/IZPACK-1114

[IZPACK-1114] Next panel not gathered correctly if it depends on panel conditions (post-fix)
[IZPACK-1115] Use <executable> and <parsable> with filesets which do not access the filesystem
Merge pull request #214 from rkrell/IZPACK-1115

[IZPACK-1115] Use <executable> and <parsable> with filesets which do not access the filesystem
Revert "Adding new attribute 'updateTrigger' for dynamic variables"

This reverts commit bc24ef5e895c493da8f0ab3008c410981cb9dc39.
Pack logic should now handle parent/child relationships, work still in progress