e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

- WITH_DEBUG_OUT for logging cascade scales
- DEBUG_STORE_IMAGES for xml matrix serialization
- DEBUG_SHOW_RESULT to see detection result

This reverts commit 618fbf55.