AI: ensure all CAs respect unit guardian status

This adds the correct behavior for the castle_switch, move_to_any_enemy and place_healers CAs.  It was already in place for the other former ExpAI CAs (except for recruiting and spread_poison, for which it does not apply).

This automatically also adds this behavior to the Healer Support Micro AI.

data/ai/lua/ca_castle_switch.lua

@@ -35,12 +35,12 @@ function ca_castle_switch:evaluation(cfg, data, filter_own)
         return 0
     end
 
-    local leader = wesnoth.units.find_on_map {
-            side = wesnoth.current.side,
-            canrecruit = 'yes',
-            formula = '(movement_left = total_movement) and (hitpoints = max_hitpoints)',
-            { "and", filter_own }
-        }[1]
+    local leader = AH.get_units_with_moves({
+        side = wesnoth.current.side,
+        canrecruit = 'yes',
+        formula = '(movement_left = total_movement) and (hitpoints = max_hitpoints)',
+        { "and", filter_own }
+    }, true)[1]
     if not leader then
         -- CA is irrelevant if no leader or the leader may have moved from another CA
         data.leader_target = nil
@@ -191,11 +191,11 @@ function ca_castle_switch:evaluation(cfg, data, filter_own)
 end
 
 function ca_castle_switch:execution(cfg, data, filter_own)
-    local leader = wesnoth.units.find_on_map {
+    local leader = AH.get_units_with_moves({
         side = wesnoth.current.side,
         canrecruit = 'yes',
         { "and", filter_own }
-    }[1]
+    }, true)[1]
 
     if AH.print_exec() then AH.print_ts('   Executing castle_switch CA') end
     if AH.show_messages() then wesnoth.wml_actions.message { speaker = leader.id, message = 'Switching castles' } end

data/ai/lua/ca_move_to_any_enemy.lua

@@ -13,11 +13,11 @@ function ca_move_to_any_enemy:evaluation(cfg, data, filter_own)
     local start_time, ca_name = wesnoth.get_time_stamp() / 1000., 'move_to_any_enemy'
     if AH.print_eval() then AH.print_ts('     - Evaluating move_to_any_enemy CA:') end
 
-    local units = AH.get_units_with_moves {
+    local units = AH.get_units_with_moves({
         side = wesnoth.current.side,
         canrecruit = 'no',
         { "and", filter_own }
-    }
+    }, true)
 
     if (not units[1]) then
         -- No units with moves left

data/ai/micro_ais/cas/ca_healer_move.lua

@@ -19,7 +19,8 @@ function ca_healer_move:evaluation(cfg, data)
 
     local healers, healers_noMP = {}, {}
     for _,healer in ipairs(all_healers) do
-        if (healer.moves > 0) then
+        -- For the purpose of this evaluation, guardians count as units without moves
+        if (healer.moves > 0) and (not healer.status.guardian) then
             table.insert(healers, healer)
         else
             table.insert(healers_noMP, healer)