Camera still shaking with proxy time_step set to 0

[rzuf79]

Noticed this while implementing pausing for my game. When the game is paused (by setting the proxy time step to 0) whilst the camera is shaking, the shake doesn't stop.

I implemented a Lazy Solution in my project by adding another check in camera.lua update function on line 429
if camera.shake and dt > 0 then

Making the shaking motion dt-dependent would prolly be slightly more elegant tho.

Including a screenie so you can suffer the unholy unstoppable shake as I did.