Remove `+` buttons from diff paste data.

It would be great if when you copy and paste the diffs you wouldn't see the pluses in there. 99% of the time I am trying to copy code to test it somewhere.

Keep the + and - and remove the line numbers from the copy paste data.

I suggest using a data-line-number attribute for the number and in the css you can use :before with content: attr(data-line-number);. This will make the line number unselectable. Via this awesome blog post https://davidwalsh.name/css-content-attr