[RFC] Add fetch_column method to mysqli

Hi Internals, I have written a new proposal in the series of improvements to mysqli extension. This one aims to add a new method mysqli_result::fetch_column as well as its functional counterpart. https://wiki.php.net/rfc/mysqli_fetch_column The RFC is very simple, but I am looking for your opinions. I also have doubts about the scope. Is the scope too limited? Should it involve a change to fetch_all as well? On the implementation part, I wonder if it could be optimized. The one I have written works but doesn't look like the most efficient way to do this. Kind Regards, Kamil Tekiela