Add mustExist attribute to file fields.
Do not print 'null' during console installation if no label is defined
for a file field. This could easily come up when the user decides to use
    a description tag for their file field instead.
Updated xsd.
[IZPACK-1090] Allow tab completion and password masking in console mode
Post-fixes:
- Really recognize fallback if ConsoleReader cannot be initialized.
On Windows, in some cases it didn't throw an error but initialized an UnsupportedTerminal which made the password field masking not working
- Use System.console() from JDK 1.6 instead of accessing System.in and System.out. Old style left als fallback for unit tests, which can't read System.console().
Merge pull request #242 from rkrell/IZPACK-1090

[IZPACK-1090] Allow tab completion and password masking in console mode
Ensure header is not shifted by 12 pixels
Ignore agentpath argument to jvm
Merge pull request #244 from ahmedlawi92/IZPACK-1139

IZPACK-1139 - Ignore agentpath argument to jvm
Merge pull request #243 from mtjandra/IZPACK-1140

[IZPACK-1140] - Ensure header is not shifted by 12 pixels
Fix for IZPACK-1009; update javadocs to have fewer missing piece of information.
RulesEngineImpl changed so that operands are not blindly added to the list of
operands for AndCondition / OrCondition / XorCondition. Instead, each condition
(and sub-condition) is checked for existence before being added; if any operand
in any expression doesn't exist, the whole expression will evaluate to false.
fix the complex expressions also
IZPACK-1109: align the warning messages to use the same language
- Ensure splash screen is only shown for GUI installations
- SplashScreen should only be shown if user has specified to use one in
  the guiprefs of their install.xml.
- New useSplashScreen modifier allows the user to specified minimum
  amount of time to display splash screen
- Notice that the splash screen must be displayed outside of the
  runnable, otherwise the splash screen will be grey
- Remove logic for adding splash screen to the Manifest
- Updating tests not the check for SplashScreen int MANIFEST.MF file
- Instead check that the "Spash.image" resource is available within the
  jar if it has been properly specified
Adding skeleton code to display a button through both console and gui
installations
Implementing skeleton to call button actions.
Remove redundant prompt method from the ConsoleField class. This prompt
method is handled by our Console class.
Merge pull request #246 from Shrafe/IZPACK-1109

Izpack 1109
Merge pull request #247 from mtjandra/IZPACK-1442

[IZPACK-1442] - Ensure not to display splash screen on console and automatic installations