fixed the way the splashscreen is called : the code has been factorized
improved splashscreen code : added PresentationScreen class
improved documentation in presentationscreen.*
(ui) added an entry menu for the internal messages; DISPLAY_INTERNAL_MESSAGES_IN_HELP_MENUITEM > MENUACCESS_TO_NTERNAL_MESSAGES
Merge branch 'feature75' into dev
Improved the way splashscreens are displayed by adding presentationscreen.* files. Code has been factorized and is well documented.