Fixed VideoCapture::open() does not release previous capture sources (Bug #3150).

VideoCapture didn't call release method and just ignored the new capture sources.
OpenCV documentation:
  bool VideoCapture::open(const string& filename);
  bool VideoCapture::open(int device);

The methods first call VideoCapture::release() to close the already opened file or camera.
Fixed "FileStorage (minor) error in doc (Feature #3151)"

It was just a typo in the documentation.
Merge pull request #1111 from nikman-ru:fix_yamldoc
Merge pull request #1109 from nikman-ru:cap_reuse_24x