Add extension key argument to Tempfile
I don't work with Tempfile often, but every time I do, I get surprised by an obscure way to pass an extension to file name.
You have to pass array, where first element is a file name and a second is a file extension (starting with a dot), which is quite a unique (not in a good way) and unusual interface for ruby.
I think a much better interface would be to use a separate key word for this.
I've researched the code and it seems we can achieve that without changing much code. I can make pr, if you think the idea is worthy