BUGFIX - Prevent zombies "jumping" when window is idle for a while
BUGFIX - Prevent zombies "jumping" when window is idle for a while

* When using requestAnimationFrame(), the browser stops rendering the
scene when the window (or tab) is idle, but when the delta is calculated
(time based) in main.js main loop, it gets a huge number, which makes all
entities update a huge amount and "jump", by passing the modifier as 0
when delta is greater than 1, the scene continues from exactly where it
was before

handrus/zombies-game,brunops/zombies-game,brunops/zombies-game