Game server/skill system: debuffs should now correctly replace buffs of the same type.
Game server/skill system: user->NPC transformations are now allowed when buffed. Resolves #272.
Game server/skill system: Unit::isBuffed() now excludes debuffs (this *may* break some existing valid behaviour). Also implemented Unit::isDebuffed().
AI server: miscellaneous cleanup
AI server: more AI cleanup, also all units are now assigned a specific unit type.
CNpc::GetEntryID() is now CNpc::GetProtoID() (latter makes more sense in context, 'entry' referred to 'database entry' which was awfully vague).
Game server/quest system: CUser::ShowEffect() is now exposed to Lua.
Game server: implemented & exposed CUser::RobAllItemParty() method (the official method name) to Lua.
Game server/party system: implemented CEbenezerDlg::GetPartyPtr().
Game server: removed handler for AG_USER_FAIL, which was only used for (really messed up) AI skill system code. This isn't used anymore (also, ???).
Game server/quest system: implemented & exposed CUser::ZoneChange(), CUser::ZoneChangeParty() & CUser::ZoneChangeClan() to Lua.
Fixed minor typo in comment.
Renamed Unit::GetType() to Unit::GetUnitType() to avoid naming conflicts with derived class methods.
Game server: corrected the behaviour of CUser::ZoneChangeClan() to behave more like official.