Itseez/opencv — pull request #1859 by SpecLad (2013-11-22 13:58:12+00:00)
Title: Gave cv::String appropriate += operators.

Note that since `String` is a reference to an immutable string, this doesn't actually change the string; it just replaces `*this` with a reference to the concatenated string.

The second commit cancels a thing I was forced to do when merging 2.4 into master - 2.4 uses `+=`, which wasn't available in master - until now, that is.