Merge branch 'release-0.4.1' into dev
      o (feature40) flush commentary's content when the reading mode changes.
      o (feature38) 'readingmodeAct' icon is not displayed anymore if no Dipydoc has been loaded : I added the DipylonUI::at_least_one_dipydoc_has_been_loaded() method which should be rewritten when the project accept several dipydocs opened.
      o (feature35) The third reading mode ('read mode') has been defined, allowing to display the translation on the fly, when the mouse hovers over an extract. The UI has been updated and the Dipydoc's format slightly amended (version #30).
      o + feature39, feature37, feature36, feature34, feature33
updated splashscreen and icons. Fixed some filenames and removed useless .png files in art/ directory
Merge branch 'feature41' into dev
updated splashscreen and icons. Fixed some filenames and removed useless .png files in art/ directory.
added art/splashscreen_500x500.xcf
Merge branch 'feature42' into dev
Added art/splashscreen_500x500.xcf
renamed some files : qt/dipylonui.* -> qt/ui.*
in all files, 'dipylonui' > 'ui' (DipylonUI > UI by example)
in all files, 'current_ui' > 'ui'
Merge branch 'feature43' into dev
cleaned up the code : dipylonui -> ui
cleaned up the UI : removed every useless icons (and the corresponding code)
Merge branch 'feature44' into dev
cleaned up the UI : removed every useless icons (and the corresponding code)
removed some icons and menus items : new, cut, copy, paste
removed AboutQt item from the menu
removed the CROSSCOMPILE_TO_WIN_USING_MXE compilation option
MainWindow::about() displays the internal messages if the (new) compilation option DISPLAY_INTERNAL_MESSAGES_IN_HELP_MENUITEM has been defined.
Merge branch 'feature45' into dev
o  cleaned up the ui (removed useless menu+icon items)
o  MainWindow::about() may now display the internal messages
o  new compilation option : DISPLAY_INTERNAL_MESSAGES_IN_HELP_MENUITEM
DipyDoc's folder have now a 'menuname' file, read by DipyDoc::read_menu_name
(modified dipydoc.*) changed functions' names : 'init_from_xml' > 'read_from_mainfile'
added MenuNames class : the program searches every 'menu name' available in the dipydoc directory
The list of the available Dipydocs appear in the File menu
added an icon in the submenu open for all dipydoc that have been identified