What is NOT done yet:
- OpenGL context of QOpenGLWindow must be made
  active before calling any GL function in scene.cc. The wrong
  GL context is active otherwise.
- cmake polishing
- final grepping for QT4 leftovers

solves a variety of problems that gcc (mainly the c++11 as default)
throws at us.

This was a necessary evil since the upcoming PM3 release relies on having the
newly added sec_struct functionality in place. The changes are additive and do
not break any existing code based on previous OST versions.

The reason is that we iterate over the atoms and add the per atom
accessibility to the current value. You can guess what happens when
calling the Accessibility function several times...