rm thirdparty library "Manhattan-style" from BornAgain project

CMakeLists.txt

GUI/coregui/CMakeLists.txt

ThirdParty/GUI/qt-manhattan-style/CMakeLists.txt

ThirdParty/GUI/qt-manhattan-style/README.md

ThirdParty/GUI/qt-manhattan-style/coreconstants.h

ThirdParty/GUI/qt-manhattan-style/doubletabwidget.cpp

ThirdParty/GUI/qt-manhattan-style/doubletabwidget.h

ThirdParty/GUI/qt-manhattan-style/doubletabwidget.ui

...y/GUI/qt-manhattan-style/extensions/simpleprogressbar.cpp

...rty/GUI/qt-manhattan-style/extensions/simpleprogressbar.h

ThirdParty/GUI/qt-manhattan-style/extensions/tabwidget.cpp

ThirdParty/GUI/qt-manhattan-style/extensions/tabwidget.h

...I/qt-manhattan-style/extensions/threelevelsitempicker.cpp

...GUI/qt-manhattan-style/extensions/threelevelsitempicker.h

ThirdParty/GUI/qt-manhattan-style/fancyactionbar.cpp

ThirdParty/GUI/qt-manhattan-style/fancyactionbar.h

ThirdParty/GUI/qt-manhattan-style/fancylineedit.cpp

ThirdParty/GUI/qt-manhattan-style/fancylineedit.h

ThirdParty/GUI/qt-manhattan-style/fancymainwindow.cpp

ThirdParty/GUI/qt-manhattan-style/fancymainwindow.h