Better heal FX / Lower wall priority

core/src/mindustry/entities/TargetPriority.java

@@ -3,6 +3,7 @@ package mindustry.entities;
 /** Higher priority blocks will always get targeted over those of lower priority, regardless of distance. */
 public class TargetPriority{
     public static final float
+    wall = -1f,
     base = 0f,
     constructing = 1f,
     turret = 2f,