MC-136886: Don't load chunks looking for features - Fixes #1438

I'm sure a few servers have crashed due to this.

Spigot-Server-Patches/MC-136886-Don-t-load-chunks-looking-for-features.patch

@@ -0,0 +1,21 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Thu, 13 Sep 2018 22:26:54 -0400
+Subject: [PATCH] MC-136886: Don't load chunks looking for features
+
+I'm sure a few servers have crashed due to this.
+
+diff --git a/src/main/java/net/minecraft/server/StructureGenerator.java b/src/main/java/net/minecraft/server/StructureGenerator.java
+index 6c2899e84d..075011748b 100644
+--- a/src/main/java/net/minecraft/server/StructureGenerator.java
++++ b/src/main/java/net/minecraft/server/StructureGenerator.java
+@@ -0,0 +0,0 @@ public abstract class StructureGenerator<C extends WorldGenFeatureConfiguration>
+                 return structurestart;
+             } else {
+                 ChunkCoordIntPair chunkcoordintpair = new ChunkCoordIntPair(i);
+-                IChunkAccess ichunkaccess = generatoraccess.getChunkProvider().a(chunkcoordintpair.x, chunkcoordintpair.z, false);
++                IChunkAccess ichunkaccess = generatoraccess.getChunkProvider().getChunkAt(chunkcoordintpair.x, chunkcoordintpair.z, false, false); // Paper - don't load chunks
+ 
+                 if (ichunkaccess != null) {
+                     structurestart = ichunkaccess.a(this.a());
+--