Allow more control over the simulation update delta time

Allows to easlily tick the engine at higher rates than the actual tick
time. For example, if you have a thread running at 20 tps, you can have
the engine ticking at 60 tps by calling forceUpdate() 3 times per tick,
one after the other.
Signed-off-by: Aleksi Sapon <QcTechs@gmail.com>