Address some issues with book limits (#1798)

The multibyte calculation has been fixed, now we actually work out which
characters take more than a byte.

Diminishing returns has been modified, previously the multiplier would zero
itself out due to floating point limitations

Spigot-Server-Patches/0405-Book-Size-Limits.patch

@@ -1,4 +1,4 @@
-From 903f06b5ea3616e0b4054b28c28d9d0b4b42a1aa Mon Sep 17 00:00:00 2001
+From 74ffd7f2292be3294d8d8c5f75525b6960266933 Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Fri, 16 Nov 2018 23:08:50 -0500
 Subject: [PATCH] Book Size Limits
@@ -22,10 +22,19 @@ index fef899ae0..468aff713 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
-index 7ae374085..bbdf729c3 100644
+index cb6d1deb8..8d06b23ea 100644
 --- a/src/main/java/net/minecraft/server/PlayerConnection.java
 +++ b/src/main/java/net/minecraft/server/PlayerConnection.java
-@@ -747,6 +747,38 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
+@@ -12,6 +12,8 @@ import java.util.Collections;
+ import java.util.Iterator;
+ import java.util.Set;
+ import javax.annotation.Nullable;
++
++import org.apache.commons.lang3.StringEscapeUtils;
+ import org.apache.commons.lang3.StringUtils;
+ import org.apache.logging.log4j.LogManager;
+ import org.apache.logging.log4j.Logger;
+@@ -747,6 +749,42 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
      }
  
      public void a(PacketPlayInBEdit packetplayinbedit) {
@@ -41,24 +50,28 @@ index 7ae374085..bbdf729c3 100644
 +                String testString = pageList.getString(i);
 +                int byteLength = testString.getBytes(java.nio.charset.StandardCharsets.UTF_8).length;
 +                byteTotal += byteLength;
++                int length = testString.length();
++                int multibytes = 0;
++                if (byteLength != length) {
++                    for (char c : testString.toCharArray()) {
++                        if (c > 127) {
++                            multibytes++;
++                        }
++                    }
++                }
++                byteAllowed += (maxBookPageSize * Math.min(1, Math.max(0.1D, (double) length / 255D))) * multiplier;
++
++                if (multibytes > 1) {
++                    // penalize MB
++                    byteAllowed -= multibytes;
++                }
++            }
++
 +            if (byteTotal > byteAllowed) {
 +                PlayerConnection.LOGGER.warn(this.player.getName() + " tried to send too large of a book. Book Size: " + byteTotal + " - Allowed:  "+ byteAllowed + " - Pages: " + pageList.size());
 +                minecraftServer.postToMainThread(() -> this.disconnect("Book too large!"));
 +                return;
 +            }
-+                int length = testString.length();
-+                int multibytes = byteLength == length ? byteLength : (int) Math.round((double) byteLength / (double) length);
-+                for (int x = 1; x < multibytes; x++) {
-+                    multiplier *= multiplier;
-+                }
-+                byteAllowed += (maxBookPageSize * Math.min(1, Math.max(0.1D, (double) length / 255D))) * multiplier;
-+                multiplier *= multiplier;
-+
-+                if (multibytes > 1) {
-+                    // penalize MB some more
-+                    byteAllowed -= length;
-+                }
-+            }
 +        }
 +        // Paper end
          // CraftBukkit start

Spigot-Server-Patches/0415-Fix-PlayerEditBookEvent.patch

@@ -1,4 +1,4 @@
-From 84094387063f1158ef9192709e67e222cb39c5ed Mon Sep 17 00:00:00 2001
+From 73b51681652bfcf42e775aaff54db6c4d29b6ce9 Mon Sep 17 00:00:00 2001
 From: Michael Himing <mhiming@gmail.com>
 Date: Sun, 16 Dec 2018 13:07:33 +1100
 Subject: [PATCH] Fix PlayerEditBookEvent
@@ -10,10 +10,10 @@ it impossible to properly cancel the event or modify the book meta
 cancelled writing
 
 diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
-index 74c570615..9741d3b23 100644
+index 8d06b23ea..a8a6e236e 100644
 --- a/src/main/java/net/minecraft/server/PlayerConnection.java
 +++ b/src/main/java/net/minecraft/server/PlayerConnection.java
-@@ -816,10 +816,13 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
+@@ -822,10 +822,13 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
  
                              this.player.setSlot(enumitemslot, CraftEventFactory.handleEditBookEvent(player, enumitemslot, itemstack1, itemstack2)); // CraftBukkit
                          } else {