message: Update AddingImages.cpp
  If-condition was always true (alpha = 0.5 is set in Line 19).
  Now the user input is checked to be between 0 and 1.
  This is correct in the tutorial code for OpenCV 2.4.
diff: @@ -27,7 +27,7 @@ int main( void )
  std::cin>>input;
  // We use the alpha provided by the user if it is between 0 and 1
  - if( alpha >= 0 && alpha <= 1 )
  + if( input >= 0 && input <= 1 )
  { alpha = input; }
  //![load]
  