Lua AIs: eliminate usages of __cfg

These are cases for which the respective variable was not accessible otherwise when the code was originally written.

data/ai/lua/ai_helper.lua

@@ -1262,12 +1262,12 @@ end
 
 function ai_helper.has_ability(unit, ability)
     -- Returns true/false depending on whether unit has the given ability
-    local has_ability = false
-    local abilities = wml.get_child(unit.__cfg, "abilities")
-    if abilities then
-        if wml.get_child(abilities, ability) then has_ability = true end
+    for _,ability_id in ipairs(unit.abilities) do
+        if (ability == ability_id) then
+            return true
+        end
     end
-    return has_ability
+    return false
 end
 
 function ai_helper.has_weapon_special(unit, special)

data/ai/lua/battle_calcs.lua

@@ -14,10 +14,10 @@ local battle_calcs = {}
 function battle_calcs.unit_attack_info(unit, cache)
     -- Return a table containing information about attack-related properties of @unit
     -- The result can be cached if variable @cache is given
-    -- This is done in order to avoid duplication of slow processes, such as access to unit.__cfg
+    -- This is done in order to avoid duplication of slow processes
 
     -- Return table has fields:
-    --  - attacks: the attack tables from unit.__cfg
+    --  - attacks: the attack tables
     --  - resist_mod: resistance modifiers (multiplicative factors) index by attack type
     --  - alignment: just that
 
@@ -32,11 +32,10 @@ function battle_calcs.unit_attack_info(unit, cache)
     end
 
     -- Otherwise collect the information
-    local unit_cfg = unit.__cfg
     local unit_info = {
         attacks = {},
         resist_mod = {},
-        alignment = unit_cfg.alignment
+        alignment = unit.alignment
     }
     local attacks = unit.attacks
     for i_a = 1,#attacks do

data/ai/lua/generic_recruit_engine.lua

@@ -758,7 +758,7 @@ return {
                 if eta_turn <= wesnoth.game_config.last_turn then
                     lawful_bonus = wesnoth.get_time_of_day(wesnoth.current.turn + eta).lawful_bonus / eta^2
                 end
-                local damage_bonus = AH.get_unit_time_of_day_bonus(recruit_unit.__cfg.alignment, lawful_bonus)
+                local damage_bonus = AH.get_unit_time_of_day_bonus(recruit_unit.alignment, lawful_bonus)
                 -- Estimate effectiveness on offense and defense
                 local offense_score =
                     (recruit_effectiveness[recruit_id].damage*damage_bonus+recruit_effectiveness[recruit_id].poison_damage)
@@ -847,7 +847,7 @@ return {
                 for attack_range, count in pairs(unit_attack_range_count[recruit_id]) do
                     bonus = bonus + 0.02 * most_common_range_count / (attack_range_count[attack_range]+1)
                 end
-                local race = wesnoth.races[wesnoth.unit_types[recruit_id].__cfg.race]
+                local race = wesnoth.races[wesnoth.unit_types[recruit_id].race]
                 local num_traits = race and race.num_traits or 0
                 bonus = bonus + 0.03 * num_traits^2
                 if target_hex[1] then

data/ai/micro_ais/cas/ca_bottleneck_move.lua

@@ -141,7 +141,7 @@ local function bottleneck_get_rating(unit, x, y, has_leadership, is_healer, on_m
         if (unit.hitpoints < unit.max_hitpoints) then
             for xa,ya in H.adjacent_tiles(x, y) do
                 local adjacent_unit = wesnoth.units.get(xa, ya)
-                if adjacent_unit and (adjacent_unit.__cfg.usage == "healer") then
+                if adjacent_unit and (adjacent_unit.usage == "healer") then
                     leadership_rating = leadership_rating + 100
                     break
                 end
@@ -306,7 +306,7 @@ function ca_bottleneck_move:evaluation(cfg, data)
 
     for _,unit in ipairs(all_units) do
         -- Is this a healer or leadership unit?
-        local is_healer = (unit.__cfg.usage == "healer")
+        local is_healer = (unit.usage == "healer")
         local has_leadership = AH.has_ability(unit, "leadership")
         local on_my_territory = BD_is_my_territory:get(unit.x, unit.y)
 
@@ -355,7 +355,7 @@ function ca_bottleneck_move:evaluation(cfg, data)
 
     local max_rating, best_unit, best_hex = 0
     for _,unit in ipairs(units) do
-        local is_healer = (unit.__cfg.usage == "healer")
+        local is_healer = (unit.usage == "healer")
         local has_leadership = AH.has_ability(unit, "leadership")
         local on_my_territory = BD_is_my_territory:get(unit.x, unit.y)