Modification of the handling of the menu bars

Created a widget for QMenuBar + centralWidget to avoid using
setMenuBar() member of QMainWindow which deletes the previous menubar.
If we want to use several menuBars later, it will better to set them
once and for all at the beginning of the program, not to recreate them
everytime we need to change the mainWindow menuBar...
Update of Menubars and replacing of tabs

Menubars are no longer handled in a separate widget and now have a
normal display, as setMenuBar() has been reimplemented in RootWindow
to overide QMainWindow's member not to delete the previous menu bar when
setting it. Also QTabWidget has been replaced by a QMdiArea for
flexibility.
New behavior of the status bar

The status bar now hides when there's nothing to show. Soon to be
configurable.
Added a few options for tabs and missings licenses

Self-explanatory title.
Adding click detection in central QMdiArea + misc

Still a few issues to work on (automaximized subwindows on launch), but
a working MDI area with both tabs and subwindows.
Added SubProgramInterface

Creation of the Qt plugins interface.
Implementation of plugins

Tested on win32 and doesn't work currently.
Mdi sub-windows are now loaded dynamically based on external libraries
containing new subprograms. Menu bars are changed based on which on is
currently focused or if the user asks for seeing the main bar.
Pin in the main menu bar added

Addition of a pin QPushButton in the main menu bar to fix it when
clicking on subprograms. Could be useful if you need to check something
in a subprogram while working on the main menu bar. Deleted a few debug
functions in MainTabs, this class is soon to be renamed.
Adding RootWindow modifications

Forgot to commit RootWindow.* for last commit.
Addition of the forgotten Import Profile option

Added a simple way to import already existing profiles. Corrected some
bugs on windows with QSettings in PreferencesWindow which didn't exist on Linux. Corrected a
few things like setEnvironmentFor(). Prepared the code for QToolBars.
Updated french translation

Updated french translations for last english strings added.
Changed menu bars behavior

Added a way to specify if the user wants to share on status bar between
Mundus and its subprograms or if we have to display two menu bars (one
for each).
Added the preferences system

Now preferences are handled in one system which loads and writes data
automatically and displays the widgets to ask the values to the user.
More details on man to come.
Added an environment handling

Environment (window title + menu bar + toolbars) is now set in its own
class which can handle more effectively every aspect of the environment
displaying in every case.
Small update for french translation

Updated a few phrases for the french translation following the last
commits.
Correction for Menu Bars

Menu Bars are now deleted "later" in Qt terms. Prevents segmentation
faults and displaying problems. Also, it's more practical that the main
menu bar is displayed first by default at the end of the program loading
instead of the last subprogram's menu bar. Click on the subprogram to
show its menu bar.
Handle the subprograms preferences

Self-explanatory; also added an applied() signal, to be used by
RootWindow
Using 100% Preference class in RootWindow

No more QSettings usage in RootWindow
Added the debugger console basis

Added a small debugger console which doesn't do anything more than
displaying Qt errors or debug for now. Also corrected a bug within
Preference system to prevent the displaying of the "modified" status
when switching profile.
Revert "Added the debugger console basis"

This reverts commit 68c8769bd0c7c3153ffd2f1b5fa10251421cbb99.