Implement Firing

[rlyshw]

Similar to #2, refer to that thread for discussion on how best to go about it. The solution to this will look almost identical to the solution of #2, so don't do this separately from #2.

[danielhinrichs]

    if(model.isFire()) {
        this.picNum = 0;
        switch(this.action) {
            case FORWARD_SE: this.action=OrcImage.FIRE_SE; break;
            case FORWARD_NE: this.action=OrcImage.FIRE_NE; break;
            case FORWARD_SW: this.action=OrcImage.FIRE_SW; break;
            case FORWARD_NW: this.action=OrcImage.FIRE_NW; break;
        }
}