Commented out debug msg and set var to local.

Initial publish. Sprinting into doors will open the door and you will sprint through.
Any zombies directly behind the door will get knocked down. There may be, on occasion, the odd incident where you will trip and fall and die horribly if the zombies are not knocked down.
To get the mod to work I had to unbind the sprint key for 80 frame ticks so the zombies would fall down and not grab you while they did, or magically jump back up again.
There is an Endurance cost based on your strength, fitness and the number of zombies knocked down.