1. someMatrix.data -> someMatrix.prt()
2. someMatrix.data + someMatrix.step * lineIndex -> someMatrix.ptr( lineIndex )
3. (SomeType*) someMatrix.data -> someMatrix.ptr<SomeType>()
4. someMatrix.data -> !someMatrix.empty() ( or !someMatrix.data -> someMatrix.empty() ) in logical expressions

This also fixes few clang build errors

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

minor build system changes (now cuda code in opencv_core is compiled using CUDA_ARCH* cmake variables)

added improved ORB implementation, convex-convex polygon intersection, eigen2x2 low-level function ...