New hint tutorial system (unfinished!)

core/src/mindustry/content/Blocks.java

@@ -2059,6 +2059,7 @@ public class Blocks implements ContentList{
             size = 7;
             hasPower = true;
             consumes.power(10f);
+            buildCostMultiplier = 0.5f;
         }};
 
         //endregion campaign

core/src/mindustry/content/UnitTypes.java

@@ -1250,6 +1250,7 @@ public class UnitTypes implements ContentList{
             defaultController = RepairAI::new;
 
             mineTier = 3;
+            mineSpeed = 4f;
             health = 500;
             armor = 5f;
             speed = 2.5f;