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

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

paper-server/nms-patches/Slot.patch

@@ -1,14 +1,5 @@
 --- a/net/minecraft/server/Slot.java
 +++ b/net/minecraft/server/Slot.java
-@@ -2,7 +2,7 @@
- 
- public class Slot {
- 
--    private final int index;
-+    public final int index; // CraftBukkit - public
-     public final IInventory inventory;
-     public int rawSlotIndex;
-     public int f;
 @@ -45,6 +45,9 @@
      }