[SPIGOT-946] Begin making use of access transforms to simplify patching.

By: md_5 <git@md-5.net>

paper-server/nms-patches/Explosion.patch

@@ -14,12 +14,7 @@
  public class Explosion {
  
      private final boolean a;
-@@ -18,15 +25,16 @@
-     private final double posX;
-     private final double posY;
-     private final double posZ;
--    private final Entity source;
-+    public final Entity source; // CraftBukkit - public
+@@ -22,11 +29,12 @@
      private final float size;
      private final List<BlockPosition> blocks = Lists.newArrayList();
      private final Map<EntityHuman, Vec3D> k = Maps.newHashMap();