Adds an API for work with deltatime things.
deltatime.get([<unit>])
For getting deltatime. (returns float number) If unit param is nothing, returns seconds. If unit param is something like seconds / minutes / hours, it will returns seconds(same as nothing) / minutes / hours.
deltatime.add(<sec>, <min>, <hour>)
For adding a time to deltatime.
If you just want to add 15 seconds, it must to be something like that:
deltatime.add(15, 0, 0)