Support *.cur files

I have noticed lack of support for *.cur files, which there are used to custom cursors ([url() value for cursor property](https://developer.mozilla.org/en-US/docs/Web/CSS/cursor/url?redirectlocale=en-US&redirectslug=CSS%2Fcursor%2Furl)). As I know most modern browsers accept other extension for cursors (e.g. png and gif), but old IE6 recognizes only curs.