A recursive find and replace tool.
Install go: https://golang.org/dl/
Then:
$ go get -u github.com/voutasaurus/s
$ s old new
This will (starting in the current directory) recursively replace the
string old by the string new in all files at or below this directory.
Files and directories beginning with . and _ are ignored.
Files and directories named vendor are also ignored.
$ s -p old new
This will do the same except it prompts for each file before doing the replacement.
Because using sed to recursively replace one word with another word is genuinely harder to figure out how to do than writing a go program to do it.