backwards movement

[sakgoyal]

I believe the the backwards movement is incorrect. the current implementation turns the wrong way around and it needs to be reversed.

I am thinking about it in terms of driving a car. when I press left (turn left) and go backwards, I will turn to the right. but in the current implementation, I am still turning left.

[rexim]

I'm actually planning to eventually use mouse for turning around, so this will be a non-issue in the future.