Determines the change rate of the time variable that
determines all movements by multiplying speeds with the duration of a frame
cycle. At 0 (default) the
time_step variable is
identical to the time of last frame cycle. At 0.5,
time_step is an average of the last 2 frame cycles, at 0.9 it is an
average over the last 10 frame cycles.
0 .. 0.99 (default = 0)
Through setting time_smooth at a high value (maximum = 0.99),
sudden 'jerks' in the game play due to hard disk operations or background
processes can be 'smoothed out'.
time_smooth = 0.666; // smooth out time_step over 3 frame cycles