allow units.remove_modifications to remove multiple types

previously it needed multiple calls to remove multiple types of modifications (which could be slow since each call involves a full rebuild of the unit).

data/test/scenarios/lua_tests/wesnoth/units/temp.txt

@@ -1 +0,0 @@
-git doesn't allow adding empty directories; delete this once any test is added

data/test/scenarios/lua_tests/wesnoth/units/test_remove_modifications.cfg

@@ -0,0 +1,120 @@
+# wmllint: no translatables
+
+#####
+# API(s) being tested: wesnoth.units.remove_modifications
+##
+# Actions:
+# adds and removed modifications
+##
+# Expected end state:
+# The asserts pass.
+#####
+#ifndef SCHEMA_VALIDATION
+{GENERIC_UNIT_TEST "test_remove_modifications" (
+    [event]
+        name = start
+        [unit]
+            side = 1
+            type = "Test Melee Quintain"
+            x = 4
+            y = 4 
+            [modifications]
+                [object]
+                    [effect]
+                        apply_to=hitpoints
+                        increase_total=20
+                    [/effect]
+                [/object]
+                [advancement]
+                    [effect]
+                        apply_to=hitpoints
+                        increase_total=5
+                    [/effect]
+                [/advancement]
+                [trait]
+                    [effect]
+                        apply_to=hitpoints
+                        increase_total=50
+                    [/effect]
+                [/trait]
+            [/modifications]
+        [/unit]
+        {ASSERT (
+            [have_unit]
+                formula="max_hitpoints=175"
+                x,y = 4,4
+            [/have_unit]
+        )}
+        #{ASSERT (
+        #    [false]
+        #    [/false]
+        #)}
+        [lua]
+            code = <<
+                local u = wesnoth.units.get(4,4)
+                u:remove_modifications({}, "trait")
+            >>
+        [/lua]
+        {ASSERT (
+            [have_unit]
+                formula="max_hitpoints=125"
+                x,y = 4,4
+            [/have_unit]
+        )}
+        [lua]
+            code = <<
+                local u = wesnoth.units.get(4,4)
+                u:remove_modifications({}, {"trait", "object", "advancement"})
+            >>
+        [/lua]
+        {ASSERT (
+            [have_unit]
+                formula="max_hitpoints=100"
+                x,y = 4,4
+            [/have_unit]
+        )}
+        [unit]
+            side = 1
+            type = "Test Melee Quintain"
+            x = 5
+            y = 4 
+            [modifications]
+                [object]
+                    a = 7
+                    [effect]
+                        apply_to=hitpoints
+                        increase_total=20
+                    [/effect]
+                [/object]
+                [advancement]
+                    a = 8
+                    [effect]
+                        apply_to=hitpoints
+                        increase_total=5
+                    [/effect]
+                [/advancement]
+                [trait]
+                    a = 9
+                    [effect]
+                        apply_to=hitpoints
+                        increase_total=50
+                    [/effect]
+                [/trait]
+            [/modifications]
+        [/unit]
+        [lua]
+            code = <<
+                local u = wesnoth.units.get(5,4)
+                u:remove_modifications({ a = 8 }, {"trait", "object", "advancement"})
+            >>
+        [/lua]
+        {ASSERT (
+            [have_unit]
+                formula="max_hitpoints=170"
+                x,y = 5,4
+            [/have_unit]
+        )}
+        {SUCCEED}
+    [/event]
+)}
+#endif

src/scripting/game_lua_kernel.cpp

@@ -3825,14 +3825,23 @@ static int intf_remove_modifications(lua_State *L)
 {
 	unit& u = luaW_checkunit(L, 1);
 	config filter = luaW_checkconfig(L, 2);
-	std::string tag = luaL_optstring(L, 3, "object");
+	std::vector<std::string> tags;
+	if(lua_isstring(L, 3)) {
+		tags.push_back(lua_check<std::string>(L, 3));
+	} else if (lua_istable(L, 3)){
+		tags = lua_check<std::vector<std::string>>(L, 3);
+	} else {
+		tags.push_back("object");
+	}
 	//TODO
 	if(filter.attribute_count() == 1 && filter.all_children_count() == 0 && filter.attribute_range().front().first == "duration") {
 		u.expire_modifications(filter["duration"]);
 	} else {
-		for(config& obj : u.get_modifications().child_range(tag)) {
-			if(obj.matches(filter)) {
-				obj["duration"] = "now";
+		for(const std::string& tag : tags) {
+			for(config& obj : u.get_modifications().child_range(tag)) {
+				if(obj.matches(filter)) {
+					obj["duration"] = "now";
+				}
 			}
 		}
 		u.expire_modifications("now");

wml_test_schedule

@@ -547,5 +547,6 @@
 0 lua_map_find
 0 mapgen_filter_range
 0 mapgen_filter_terrain
+0 test_remove_modifications
 0 simulate_combat_clone_adjacent
 0 simulate_combat_occupied