Adding put equivalents of d2o/d3o to Gdiffsplit!

[merijn]

When resolving conflicts I like to put the final resolution to the parent buffer(s) so that any conflicts I've already looked at collapse into the no changes fold. I can simply use, but writing :diffput //2 or :diffput //3 gets kinda tedious, so it would be nice to have put equivalents of the d2o/d3o commands so I can just use d2p/d3p to accomplish this.