Twobier's submission

* First performance tweaks

* further tweaks

* collect into a treemap

* Tweak JVM options

* Inline rounding into collector

* reduce some operations

* oops, add missing braces

* tweak JVM options

* small fixes

* add min and max to processing

* fix min

* remove compact strings

* replace sumWithCompensation with naive sum implementation

* use UseShenandoahGC

* integrate mmap

* integrate mmap

* Fix messed up array logic

* Set jdk version

calculate_average_twobiers.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+#
+#  Copyright 2023 The original authors
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+source "$HOME/.sdkman/bin/sdkman-init.sh"
+sdk use java 21.0.1-tem 1>&2
+JAVA_OPTS="-XX:+UseShenandoahGC -XX:+UseStringDeduplication -XX:+UseTransparentHugePages -da"
+java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_twobiers