Core/Guilds: Rewrite & fix Guild News system

*Guild News now loads and saves properly
*Records news for loot/purchasing/achievements/crafting
*Stick/unstick news works

Note: News for guild achievements & dungeon encounters not implemented
Core/Arenas: Fix crash

character_arena_stats has no personal rating field
Merge pull request #889 from roc13x/master

Guild News rewrite & Arena crashfix