- CV_RGB() macro is moved into opencv2/imgproc.hpp from imgproc_c.h
- samples/cpp/filestorage_base64.cpp is dropped

also add comments explaining the change

- use per-module includes instead of "opencv.hpp"
- unused function warnings
- undefined macro warning

* Update samples

* Update calib3d.hpp

* Update calib3d.hpp

* Update calib3d.hpp

* Update calib3d.hpp

Fix error usage in HitMiss tutorial, and improved the visualization results (#7978)

* Fix error usage in HitMiss tutorial, and improved the visualization results

Fix error usage in HitMiss tutorial, and improved the visualization results

* Update HitMiss.cpp

* Update HitMiss.cpp

Use directly the doxygen snippet command for the Changing the contrast and brightness of an image tutorial. Extend the tutorial with a pratical example and with a gamma correction method to adjust the brightness of an image.

Original commit is a5f19f7dd6ae5bc93f73e0417a9e0bfd34c01672

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

Also fixed some typos and code alignment
Also adapted tutorial CPP samples
Fixed some identation problems

These codes should be included into regular builds.