message: release: OpenCV 3.4.18
diff: #define CV_VERSION_MAJOR 3
  #define CV_VERSION_MINOR 4
  #define CV_VERSION_REVISION 18
  -#define CV_VERSION_STATUS "-pre"
  +#define CV_VERSION_STATUS ""
  #define CVAUX_STR_EXP(__A) #__A
  #define CVAUX_STR(__A) CVAUX_STR_EXP(__A)
  