Added the graphical interface.

 On branch master
 Changes to be committed:
	new file:   build-calculator-clang-Debug/Makefile
	new file:   build-calculator-clang-Debug/calculator
	new file:   build-calculator-clang-Debug/main.o
	new file:   build-calculator-clang-Debug/main_window.o
	new file:   build-calculator-clang-Debug/qrc_qml.cpp
	new file:   build-calculator-clang-Debug/qrc_qml.o
	new file:   calculator/calculator.pro
	new file:   calculator/calculator.pro.user
	new file:   calculator/deployment.pri
	new file:   calculator/main.cpp
	new file:   calculator/main.qml
	new file:   calculator/main_window.cpp
	new file:   calculator/main_window.h
	new file:   calculator/main_window.hpp
	new file:   calculator/qml.qrc