Update overworld map properties and overlay functionality

- Changed the included assembly file for custom overworld to version 3 for improved features.
- Enhanced documentation in the overworld loading guide to clarify overlay effects and configurations.
- Refactored MapPropertiesSystem to support overlay previews and improved mosaic controls.
- Added functionality for loading vanilla overlays and displaying overlay descriptions in the editor.
- Updated UI components in OverworldEditor to integrate new overlay settings and preview options.

assets/asm/yaze.asm

@@ -15,7 +15,7 @@ endif
 !ZS_CUSTOM_OVERWORLD = 1
 
 if !ZS_CUSTOM_OVERWORLD != 0
-  incsrc "ZSCustomOverworld.asm"
+  incsrc "ZSCustomOverworld_v3.asm"
 endif
 
 }