Update CMake search for Qt5 componets to be consistent
with recommended practice from Kitware.
(see https://blog.kitware.com/cmake-finding-qt5-the-right-way/)
Incorporate ability to build cppcheck-gui with Qt Charts
via CMake switch. Option "WITH_QCHARTS" will enable
search for Qt Charts to Qt5 component search and add
build flag "HAVE_QCHART".