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
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
Pack logic should now handle parent/child relationships, work still in progress
First iteration of TreePacksPanel refactorings.
- Remove several redundant methods that should be handled by PacksModel
- Do not instantiate a new PacksModel everytime you view the
  TreePacksPanel
- Some renaming of variables and methods
Second iteration of refactoring TreePacks and its PackModel.
- Removed redundant methods and method calls
- Narrow the focus of TreePacksPanel to provide the correct view rather
  than handling pack data.
Ensure that the TreePacksConsolePanel uses the PacksModel for keeping
track of pack data.
Third iteration of PacksModel Refactoring.
- Ensure partial checkbox information is obtained from packsModel
- Updates names of varaibles to be more clear and follow camelCase
  format
Ensure the onSelect and onDeselect attributes do not alter required
packages. Ensure the onSelect and onDeselect attributes do not alter
packages that do not have their dependencies resolved.
Further improvements to console TreePacksPanel.
- Show children of a parent underneath a pack
- Show dependencies of a pack underneath a pack
- Show if a pack is required underneath a pack
Merge branch 'master' into IZPACK-1113

Conflicts:
	izpack-compiler/src/main/java/com/izforge/izpack/compiler/CompilerConfig.java
Ensure to try to use internationalized strings first in
TreePacksConsolePanel.
Added auto-generation of button mnemonics based on button's text caption to ButtonFactory.
Added reserved navigator button mnemonics so navigator buttons shortcuts always
have precedence over panel button shortcuts.
Refresh panel button mnemonics map whenever the panel is switched so we don't
have collisions of button mnemonics from different panels.
[IZPACK-1125] ConfigurationInstallerListener - footer comments are not preserved
- Ensure to call saveData when hitting previous.
- This has been updated because of the changes from issue IZPACK-1114, the
  executeValidationActions was removed.