Use Log4j IOStreams to redirect System.out/err to logger

Log4j2 provides an optimized implementation of PrintStream that
redirects its output to a logger. Use it instead of a custom
implementation for minor performance improvements and some fixes.

With the old implementation, each call to System.print()
results in a separate line, even though it should not result in
a line break. Log4j's implementation handles it correctly.

Spigot-Server-Patches/Use-Log4j-IOStreams-to-redirect-System.out-err-to-lo.patch

@@ -0,0 +1,49 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Minecrell <dev@minecrell.net>
+Date: Mon, 18 Sep 2017 12:00:03 +0200
+Subject: [PATCH] Use Log4j IOStreams to redirect System.out/err to logger
+
+Log4j2 provides an optimized implementation of PrintStream that
+redirects its output to a logger. Use it instead of a custom
+implementation for minor performance improvements and some fixes.
+
+With the old implementation, each call to System.print()
+results in a separate line, even though it should not result in
+a line break. Log4j's implementation handles it correctly.
+
+diff --git a/pom.xml b/pom.xml
+index 98972114d..aff997468 100644
+--- a/pom.xml
++++ b/pom.xml
+@@ -0,0 +0,0 @@
+             <scope>runtime</scope>
+         </dependency>
+ 
++        <!-- Paper - Add additional Log4J dependencies -->
++        <dependency>
++            <groupId>org.apache.logging.log4j</groupId>
++            <artifactId>log4j-iostreams</artifactId>
++            <version>2.8.1</version>
++        </dependency>
++
+         <!-- testing -->
+         <dependency>
+             <groupId>junit</groupId>
+diff --git a/src/main/java/net/minecraft/server/DedicatedServer.java b/src/main/java/net/minecraft/server/DedicatedServer.java
+index b3f1aa999..854455711 100644
+--- a/src/main/java/net/minecraft/server/DedicatedServer.java
++++ b/src/main/java/net/minecraft/server/DedicatedServer.java
+@@ -0,0 +0,0 @@ public class DedicatedServer extends MinecraftServer implements IMinecraftServer
+         */
+         // Paper end
+ 
+-        System.setOut(new PrintStream(new LoggerOutputStream(logger, Level.INFO), true));
+-        System.setErr(new PrintStream(new LoggerOutputStream(logger, Level.WARN), true));
++        // Paper start - Use Log4j IOStreams
++        System.setOut(org.apache.logging.log4j.io.IoBuilder.forLogger(logger).setLevel(Level.INFO).buildPrintStream());
++        System.setErr(org.apache.logging.log4j.io.IoBuilder.forLogger(logger).setLevel(Level.WARN).buildPrintStream());
++        // Paper end
+         // CraftBukkit end
+ 
+         thread.setDaemon(true);
+--