AD Stats

New
- Skill and Stat milestones now show up as real advancements (press L).
- Leaderboard commands: /adstats top <stat> and /adstats top skills <skill> show the top players.
- The server can now tune almost everything about ADStats without a new release: leveling speed per skill, a level cap, attribute bonus strength, whether PvP damage counts, the boss bar, sync/autosave timing, the leaderboard, announcement timing, and the milestone advancements can all be turned on/off or adjusted in config/adstats-common.toml.

Balance
- Luck bonus per level reduced, so it stays in line with how strong luck effects are elsewhere in the game.
- Toughness bonus per level reduced, so it's proportional to the other stat bonuses.