Refactor WorldMap to support functional sectors

[Vankata453]

Refactored WorldMap class, which supports functional sectors. Teleporting to a different sector in the same worldmap is now possible. This removes the need for using the unintuitive in most cases alternative, which is having multiple worldmaps.

WorldMapSector is the new class which handles sectors in a worldmap. It inherits SectorBase, which is a base for the Sector class that is used in levels, but only with its basic properties and functions included. This allows WorldMapSector to be parsed using WorldMapSectorParser, which inherits SectorParser.

Teleporting from one sector to another is possible both with scripting and using teleporters.

This pull request also features some general organizations/improvements to worldmap-related code:

• Editor worldmap object classes and main functional worldmap object classes have been merged into one for easier management.
• A fix for the scripting issue, previously attempted to be fixed in Fix dead scripting objects when testing worldmaps #2375, is incorporated in this PR, where the approach taken is to keep a reference to each GameObject's parent GameObjectManager.

Fixes #1511.

[mrkubax10]

Could you fix build errors?

[mrkubax10]

Could you fix merge conflicts?