Game server: implemented support for the commander PM chat type. Renamed the old unused chat types to more accurately describe their current purpose, and added the new ones as per #209.
Game server/skill system: tweaked saved skill recasting to use MagicInstance directly, and ensured transformations were both recast correctly, and removed properly when entering a zone that does not support the transformation type. Refs #260.
Game server/skill system: attempted to clarify some of ExecuteType4()'s behaviour.
Game server/skill system: fixed bug with previous commit that caused recast transformation skills to not show the icon (caster/target IDs weren't set). Also implemented base prereq checks for type 4 (buff/debuff) skills. Resolves #260.
Game server/skill system: as only users can use transformations, all transformation-related code is now consistently placed in CUser. Also allowed for MORAL_SIEGE_WEAPON.