fix missing "opencv2/core/opencl" headers from core module (updated install list)

* update createsamples

adds command-line option -rngseed
replaces rand() -> theRNG()

* Update utility.cpp

* apps(createsamples): fix warpPerspective pixels access bug

Implementation of bit-exact resize. Internal calls to linear resize updated to use bit-exact version. (#9468)

Added a couple of comments to the interface of traincascade.cpp in order to tell user about the usage of traincascade.cpp file and to learn how Github submitting works

(2.4) Backports from master branch (#7854)

Original commit is a5f19f7dd6ae5bc93f73e0417a9e0bfd34c01672

All of these: (performance) Prefer prefix ++/-- operators for non-primitive types.
[modules/calib3d/src/fundam.cpp:1049] -> [modules/calib3d/src/fundam.cpp:1049]: (style) Same expression on both sides of '&&'.