Implemented piano keyboard, clicking keys adds note to the score

picts/pianokey.png

spare_parts/scalable/pianokey.svg

src/libs/core/CMakeLists.txt

src/libs/core/instruments/tpianobg.cpp

src/libs/core/instruments/tpianobg.h

src/libs/core/tnootkaqml.cpp

src/libs/core/tnootkaqml.h

src/nootka.qrc

src/qml/MainWindow.qml

src/qml/instruments/Instrument.qml