gui: manhattan style implemented

AppGUI/appgui.pro

AppGUI/coregui/coregui.pro

AppGUI/coregui/experimentmanager/experimentmanager.cpp

AppGUI/coregui/experimentmanager/experimentmanager.h

AppGUI/coregui/fitmanager/fitmanager.cpp

AppGUI/coregui/fitmanager/fitmanager.h

AppGUI/coregui/images/mode_exp.png

AppGUI/coregui/images/mode_fit.png

AppGUI/coregui/images/mode_sample.png

AppGUI/coregui/images/mode_simul.png

AppGUI/coregui/images/mode_welcome.png

AppGUI/coregui/mainwindow/imode.cpp

AppGUI/coregui/mainwindow/imode.h

AppGUI/coregui/mainwindow/main.cpp

AppGUI/coregui/mainwindow/mainwindow.cpp

AppGUI/coregui/mainwindow/mainwindow.h

AppGUI/coregui/mainwindow/taskselectorwidget.cpp

AppGUI/coregui/mainwindow/taskselectorwidget.h

AppGUI/coregui/mainwindow/welcomemode.cpp

AppGUI/coregui/mainwindow/welcomemode.h