Show infravision in the UI left pane

[marvalis]

Currently there is no way for the player to tell if he has infra-vision or not, and how far it goes by just looking at the screen. You can see it in the 'c'haracter menu.
I suggest showing the player that he has infravision in the left pane, maybe as a temporary effect: Infravision range x.
Alternatively you could also mark the area around the player, or provide an option to turn the highlight on and off.