Fixed #1313.

In some cases STK was barely playable because of very low refresh rates (25-30Hz).

This may be caused by last changes in display drivers. I remember that previously refresh rates for resolution were in order from the lowest to the greatest. Now I see it in reversed order.
Irrlicht didn't check refresh rates and always set the last available for specified resolution.

Now we use the highest available refresh rate.

Perhaps we should use xrandr library instead of vidmode. It should be much smarter and maybe would solve some multimonitor issues.