1.2 released

Remove the unused MBar field from the AbstractMDIApplication
The MessageArea interface is now not swing-related. A SwingMessageArea interface has exactly the same API and swing-related
The ErrorLogger is now in the bootstrap package
Add a new DefaultErrorLogger default implementation, and use by default this DefaultErrorLogger in the AbstractJFXApplication and the AbstractApplication classes
The MDIApplication has now a method to get the error logger
Change all the printStackTrace() methods to rather use the ErrorLogger
Add a system to bookmark a menu and allows to add actions or components in a previously bookmarked menu
Add a new fireUpdateSelectedTab method in the MDIApplicationListener to be fired when the selected tab has changed
All the methods in the MDIApplicationListener interface now do nothing by default
Fix the usage of dynamic menus in some use cases
Put all the methods which set progress in the Statusbar in the Swing EDT