Remove wall-time / unused skip tick protection (#11412)

Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.

patches/server/0600-Manually-inline-methods-in-BlockPosition.patch

@@ -0,0 +1,63 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Spottedleaf <Spottedleaf@users.noreply.github.com>
+Date: Mon, 6 Jul 2020 22:48:48 -0700
+Subject: [PATCH] Manually inline methods in BlockPosition
+
+
+diff --git a/src/main/java/net/minecraft/core/BlockPos.java b/src/main/java/net/minecraft/core/BlockPos.java
+index 73d7b5148e3a92c085b08303589827a6f0ae8d07..12ff8886bb53ca15db745989c25b9bd2f45335e4 100644
+--- a/src/main/java/net/minecraft/core/BlockPos.java
++++ b/src/main/java/net/minecraft/core/BlockPos.java
+@@ -570,9 +570,9 @@ public class BlockPos extends Vec3i {
+         }
+ 
+         public BlockPos.MutableBlockPos set(int x, int y, int z) {
+-            this.setX(x);
+-            this.setY(y);
+-            this.setZ(z);
++            this.x = x; // Paper - Perf: Manually inline methods in BlockPosition
++            this.y = y; // Paper - Perf: Manually inline methods in BlockPosition
++            this.z = z; // Paper - Perf: Manually inline methods in BlockPosition
+             return this;
+         }
+ 
+@@ -637,19 +637,19 @@ public class BlockPos extends Vec3i {
+ 
+         @Override
+         public BlockPos.MutableBlockPos setX(int i) {
+-            super.setX(i);
++            this.x = i; // Paper - Perf: Manually inline methods in BlockPosition
+             return this;
+         }
+ 
+         @Override
+         public BlockPos.MutableBlockPos setY(int i) {
+-            super.setY(i);
++            this.y = i; // Paper - Perf: Manually inline methods in BlockPosition
+             return this;
+         }
+ 
+         @Override
+         public BlockPos.MutableBlockPos setZ(int i) {
+-            super.setZ(i);
++            this.z = i; // Paper - Perf: Manually inline methods in BlockPosition
+             return this;
+         }
+ 
+diff --git a/src/main/java/net/minecraft/core/Vec3i.java b/src/main/java/net/minecraft/core/Vec3i.java
+index df4c9b275752ad97a4efe9380ae0d511ee760695..02367ef1371dde94ff6c4cd40bd32e800d6ccaaf 100644
+--- a/src/main/java/net/minecraft/core/Vec3i.java
++++ b/src/main/java/net/minecraft/core/Vec3i.java
+@@ -16,9 +16,9 @@ public class Vec3i implements Comparable<Vec3i> {
+             vec -> IntStream.of(vec.getX(), vec.getY(), vec.getZ())
+         );
+     public static final Vec3i ZERO = new Vec3i(0, 0, 0);
+-    private int x;
+-    private int y;
+-    private int z;
++    protected int x; // Paper - Perf: Manually inline methods in BlockPosition; protected
++    protected int y; // Paper - Perf: Manually inline methods in BlockPosition; protected
++    protected int z; // Paper - Perf: Manually inline methods in BlockPosition; protected
+ 
+     public static Codec<Vec3i> offsetCodec(int maxAbsValue) {
+         return CODEC.validate(