coa.2: guard CoA data shapes (custom classes, comm-seeded records, ungeared chars)

Fixes login/UI crashes on Vol'jin - CoA Beta:
- DataStore_Inventory: GetAverageItemLevel returns 0 not nil (Altoholic sort
  + AccountSummary iLvl format); guard login AIL broadcast and 0/0 average.
- DataStore_Pets: GetNumPets returns 0 for unscanned companion table instead
  of assert-crashing TabCharacters.
- DataStore_Characters: GetColoredCharacterName tolerates nil name.
- Altoholic/Characters.lua: GetLineType returns nil for stale line id.

Stamp -coa.2 + X-Edited-By: Exiles on touched addons; README CoA changelog.

DataStore_Inventory/DataStore_Inventory.lua

@@ -88,7 +88,7 @@ local function GetAIL(alts)
 	local out = {}
 	
 	local character = DataStore:GetCharacter()	-- this character
-	local ail = DataStore:GetAverageItemLevel(character)
+	local ail = DataStore:GetAverageItemLevel(character) or 0	-- CoA: guard nil so the login AIL broadcast can't crash (mirrors the alt loop below)
 	table.insert(out, format("%s:%d", UnitName("player"), ail))
 
 	if strlen(alts) > 0 then
@@ -162,7 +162,7 @@ function ScanInventory()
 		end
 	end
 	
-	addon.ThisCharacter.averageItemLvl = totalItemLevel / itemCount
+	addon.ThisCharacter.averageItemLvl = (itemCount > 0) and (totalItemLevel / itemCount) or 0	-- CoA: ungeared char => itemCount 0; avoid 0/0 nan
 	addon.ThisCharacter.lastUpdate = time()
 end
 
@@ -202,7 +202,7 @@ local function _GetInventoryItemCount(character, searchedID)
 end
 	
 local function _GetAverageItemLevel(character)
-	return character.averageItemLvl
+	return character.averageItemLvl or 0		-- CoA: chars known only via guild comm / not yet scanned have no iLvl; callers do arithmetic on it (Altoholic sort, AccountSummary format)
 end
 
 local sentRequests		-- recently sent requests