JBIDE-18670 HTML5 Palette: Palette model refactoring

new palette model implemented
It should be just
    version = (IonicVersion)((PaletteItemDropCommand)command).getPaletteItem().getCategory().getVersionGroup().getVersion();;
even without check for instance of, because NewIonicWidgetWizard may not be initialized with other version than IonicVersion, it is an error that should cause failure.

The same should be done in NewJQueryWidgetWizard.setCommand.