Tree-like objective node structure (#7152)

* overall structure

* overall layout

* field interpreter

* less bloated UI

* scroll pan't

* strip off the 'Marker' suffix

* e

* all (hopefully all...) interpreters finished.

* onset

* two, four

* i don't understand how icon mappings work.

* separate remover and indexer

* some cleanups

* untested mobile support

* contrib

* ok anuke

* fix conflicts 2

* hidden

core/src/mindustry/game/Rules.java

@@ -7,7 +7,6 @@ import arc.util.serialization.*;
 import arc.util.serialization.Json.*;
 import mindustry.*;
 import mindustry.content.*;
-import mindustry.game.MapObjectives.*;
 import mindustry.graphics.g3d.*;
 import mindustry.io.*;
 import mindustry.type.*;
@@ -124,9 +123,9 @@ public class Rules{
     public ObjectSet<String> researched = new ObjectSet<>();
     /** Block containing these items as requirements are hidden. */
     public ObjectSet<Item> hiddenBuildItems = Items.erekirOnlyItems.asSet();
-    /** Campaign-only map objectives. */
-    public Seq<MapObjective> objectives = new Seq<>();
-    /** Flags set by objectives. Used in world processors. n*/
+    /** In-map objective executor. */
+    public MapObjectives objectives = new MapObjectives();
+    /** Flags set by objectives. Used in world processors. */
     public ObjectSet<String> objectiveFlags = new ObjectSet<>();
     /** If true, fog of war is enabled. Enemy units and buildings are hidden unless in radar view. */
     public boolean fog = false;