Note that this func does not get the current time! It is meant for
timing pieces of code.
Also, this func is not very precise at the moment,
since SDL's timer is used. This will change in some time in the future when modules for timers
with higher resolutions are created.
Modules
love.graphics
love.audio
love.physics
love.mouse
love.keyboard
love.joystick
love.filesystem
love.timer
love.system