Refactored Persistance managed by SpawnManager for groups, and added … (#53)

* Refactored Persistance managed by SpawnManager for groups, and added Persistence for buildables
* get last file based on the iteration number
* Working persistence of everything as a MVP version

classes/fleetClasses/GlobalFleetManager.lua

@@ -8,7 +8,7 @@ GlobalFleetManager.start = function(database)
 
     local logger = Spearhead.LoggerTemplate.new("CARRIERFLEET", "INFO")
 
-    local all_groups = Spearhead.DcsUtil.getAllGroupNames()
+    local all_groups = Spearhead.classes.helpers.MizGroupsManager.getAllGroupNames()
     for _, groupName in pairs(all_groups) do
         if Spearhead.Util.startswith(string.lower(groupName), "carriergroup" ) == true then
             logger:info("Registering " .. groupName .. " as a managed fleet")