Also cv::, cv::gpu:: and cv::ocl:: namespace prefixes can be safely omitted
inside CV_ENUM and CV_FLAGS

It is already marked as a gtest 1.7.0

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

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

Fixed issues: #2737 #2848

- add syntetic images generation function to ts
- use generated syntetic images

fix compilation OpenCV with cxx11 under Ubuntu with clang and gcc 4.7