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_Pets/DataStore_Pets.lua

@@ -70,7 +70,7 @@ local function _GetPets(character, companionType)
 end
 
 local function _GetNumPets(pets)
-	assert(type(pets) == "table")		-- this is the pointer to a pet table, obtained through GetPets()
+	if type(pets) ~= "table" then return 0 end		-- CoA: char may have no scanned CRITTER/MOUNT table yet; upstream assert() crashed TabCharacters
 	return #pets
 end