(UserPanel.java)
add constrain to disable casle selection (by mouse click) when castle does not belong to current user

(MainWindow.java, ConfigManager.java)
add action to load/save file with FileSelector dialog. Only XML extension is suported. Xml extention is forced when user provide file name with other then .xml extension.
Add Epoch, and King labels in top panel of main window.

(Game.java)
Add filename support for save/load file with FileChooser
add method getCurrentUser to facilitate access to current user object

(User.java)
same amount of coins is created when user created, just with different size (to be more representative on user panel)

(SaveConfigAction.java, LoadConfigAction.java)
implemented to support save/load with filechooser dialog
actually action are used only from UI thread, but later may be refactored to use from other thread.

(ExtensionFileFilter.java)
XML filter to user with filechooser dialog