Refactor world composition for trap items

Currently, trap items are mapped to a badge in per-game, IGameConfiguration.traps, as { "itemName": "badge" }; this can be merged on world load to IWorldConfiguration.items:

• Merge into "items" as { "priority": ItemPriorityEnum.Custom, "badge": "..." }
• Remove the specialized IWorldManager.getTrapBadge function and any logic that depends on it - i.e. item priority / badge lookup
• Remove the PriorityEnum.Trap entry - all composed trap items should be considered "custom", and can be overwritten by the player (see #12 (closed))