Add [remove_time_area] and allow [time_area] remove=yes to take an id list

[remove_time_area] is syntatic sugar but it's used to implement
[time_area] remove=yes now, just like [remove_event]/[event].

changelog

@@ -153,6 +153,9 @@ Version 1.13.1+dev:
    * Added a new [difficulty] tag for defining a campaign's difficulty level
    * Add new syntax for [option], similar to the new difficulty syntax
    * Add [test_condition] ActionWML that tells why a conditional failed (for debugging)
+   * Add [remove_time_area] WML tag which takes a comma-separated list of time
+     area ids, and make [time_area] id= accept a comma-separated list when
+     using remove=yes as well.
  * Editor:
    * Added Category field and color sliders to the Edit Label panel.
  * Miscellaneous and bug fixes:

data/lua/wml-tags.lua

@@ -1407,14 +1407,21 @@ function wml_actions.remove_shroud(cfg)
 end
 
 function wml_actions.time_area(cfg)
-	local remove = cfg.remove
-	if remove then
-		wesnoth.remove_time_area(cfg.id)
+	if cfg.remove then
+		wml_actions.remove_time_area(cfg)
 	else
 		wesnoth.add_time_area(cfg)
 	end
 end
 
+function wml_actions.remove_time_area(cfg)
+	local id = cfg.id or helper.wml_error("[remove_time_area] missing required id= key")
+
+	for w in utils.split(id) do
+		wesnoth.remove_time_area(w)
+	end
+end
+
 function wml_actions.replace_schedule(cfg)
 	wesnoth.replace_schedule(cfg)
 end