Don't select images when expanding them

This fixes one of my greatest annoyances with RES, it adds '-X-user-select: none' to expando image icons so you don't accidentally select the image below.

Also, 'user-select' isn't actually recognised in Firefox or Chrome [as explained here](https://developer.mozilla.org/en-US/docs/Web/CSS/user-select "ignore the warning, it's about the fact that it's not in any standards recommendation"), so I removed both instances from res.css.
Currently the only problem is it throws a CSS warning/error. Another problem which is less likely is that if it does become a standard property then its behaviour could change too, which might cause it to stop working