implement the core profile support as discussed in the redmine system
mentioned in issue #16
mentioned in issue #11
waiting for #20 as glew causes problems when loading opengl functions in core profile
CoreWidget: QGLWidget to QOpenGLWidget
Reassigned to @tenter
triggers opengl debug output: GL_INVALID_OPERATION error generated. Invalid VAO/VBO/pointer usage.
QPainter and QPaintEngine are incompatible with core profile: https://bugreports.qt.io/browse/QTBUG-33535