ThreeCore

- Added scripts/utils html file, added createFromJson function to itemStackBuilder
- Fixed readString in many packets
- Made list of script accessors open for other mods to hook in
- Fixed crash when entity doesnt have jump height attribute
- Added ability_container_time texture variable, fixed models not having correct visibility when not in armor
- Added ItemGroupFiller utility class to place items inbetween vanilla items in creative tabs, so their place makes more sense
- Slight changes to ItemGroupFiller and how lifetime of ability containers work