Implemented a simple hook.Exists function to check if a hook exists or not.

Purpose:
A cleaner way to check if a hook exists instead of having to do something ugly like ( hool.GetTable()[ "event" ][ "identifier" ] )

Added hook..Temporary() function to hook module.

Purpose: Provides a quick and simple way to create hooks that will remove themselves after a certain amount of times being ran.

Args: string hook_event, any identifier, integer max_runs, function func

Note: If only event_name, name and max_runs are provided, it will assume that the max_runs is the hook functions and that this hook should only be ran once before removing itself. This is a failsafe

Utilized the same logic as hook.Add and hook.Remove inside hook.Temporary to reduce overhead from double validating args