Cleanup ExprWorld and fix time state values

[sovdeeth]

Problem

former event-location's world was ambiguous and returning the wrong value sometimes, since former (event-location's world) was not properly handled.

Solution

Cleans up ExprWorld to modern standards. Reworks the get() method so that no matter the type of the input, if timestates are used it will return the correct value.

Testing Completed

Manual confirmation with:

on player teleport: 
    broadcast "%former (event-location's world)%"
    broadcast "%former (event-entity's world)%"
    broadcast "%(former event-location)'s world%"
    broadcast "%(former event-entity)'s world%" # intentionally errors
    broadcast "%former world%"
    broadcast "getFrom: %event.getFrom()%"
    broadcast "getTo: %event.getTo()%"

Supporting Information

---

Completes: Fixes #8200
Related: none
AI assistance: none

stale