put the focus pos slightly in front of the camera.
more logical, half-parallel movement of the camera.

as in, pressing multiple keys works. more or less, there is a short stop
when you press an additional key.
add focus to camera position.
look around with mouse.

not finished, doesn't really allow you to turn around, should probably
use two degrees of rotation. needs some research before i can implement
it.
support wasd navigation.