PaperPR - Projectile load/save limit per chunk

- Dropped "Add option to disable saving projectiles to disk" in favor of the above patch
 - Config migration is automatic. If "gameplay-mechanics.save-projectiles-to-disk" was set to false in purpur.yml, "projectile-load-save-per-chunk-limit" will be set to 0 in paper.yml (resulting in unchanged behaviour)

patches/server/0079-Add-obfhelpers-for-plugin-use.patch

@@ -0,0 +1,18 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: William Blake Galbreath <Blake.Galbreath@GMail.com>
+Date: Wed, 1 Jan 2020 20:12:39 -0600
+Subject: [PATCH] Add obfhelpers for plugin use
+
+
+diff --git a/src/main/java/net/minecraft/server/ItemStack.java b/src/main/java/net/minecraft/server/ItemStack.java
+index e7759f2481..2c908a6040 100644
+--- a/src/main/java/net/minecraft/server/ItemStack.java
++++ b/src/main/java/net/minecraft/server/ItemStack.java
+@@ -644,6 +644,7 @@ public final class ItemStack {
+         return this.tag;
+     }
+ 
++    public NBTTagCompound getOrCreateSubTag(String s) { return a(s); } // Purpur - OBFHELPER
+     public NBTTagCompound a(String s) {
+         if (this.tag != null && this.tag.hasKeyOfType(s, 10)) {
+             return this.tag.getCompound(s);