java.lang.NegativeArraySizeException & java.lang.ArrayIndexOutOfBoundsException when Rendering Images with "High" Resolution

Hi,

I'm currently trying to render Images with high resolutions and face some Issues.
When trying to render in a resolution higher than 35520x19980 the problems beginn to show up.
1. When Trying to render in 36480x20520 Chunky crashes after scene Loading with this Error
```
Loading scene took 0m 1s

Unchecked exception caused Chunky to close.
java.lang.NegativeArraySizeException
at se.llbit.chunky.renderer.scene.Scene.initBuffers(Scene.java:366)
at se.llbit.chunky.renderer.scene.Scene.importFromJson(Scene.java:2535)
at se.llbit.chunky.renderer.scene.Scene.fromJson(Scene.java:2379)
at se.llbit.chunky.renderer.scene.Scene.loadDescription(Scene.java:2501)
at se.llbit.chunky.renderer.scene.Scene.loadScene(Scene.java:473)
at se.llbit.chunky.renderer.scene.SynchronousSceneManager.loadScene(SynchronousSceneManager.java:146)
at se.llbit.chunky.main.Chunky.doHeadlessRender(Chunky.java:159)
at se.llbit.chunky.main.Chunky.main(Chunky.java:208)

Failed to launch Chunky. Command used:
/usr/lib/jvm/java-8-oracle/jre/bin/java -Xmx153600m -Dchunky.home=/home/user/.chunky -classpath /home/user/.chunky/lib/chunky-core-1.4.5.jar:/home/user/.chunky/lib/commons-math3-3.2.jar se.llbit.chunky.main.Chunky -texture /home/user/txtpack.zip -target 1 -render resolutiontest
```

2. When trying to render even Larger Images with a resolution of 61440x34560 the scene is successfull loaded, but chunky crashed while rendering with this error
```Loading octree took 0m 0s 1)
Loading regions took 0m 0s1)
Loading entities took 0m 0s)
Loading chunks: 100.0% (1,024 of 1,024)
Loading chunks took 0m 3s 1)
Finalizing octree took 0m 1s
Loading scene took 0m 13s
Rendering: 0.0% (0 of 1) [ETA=1011703407:30:07]

Render worker 1 crashed with uncaught exception.
java.lang.ArrayIndexOutOfBoundsException: 2075259000
at se.llbit.chunky.renderer.RenderWorker.work(RenderWorker.java:135)
at se.llbit.chunky.renderer.RenderWorker.run(RenderWorker.java:71)
```

Both Issues are showing up regardless of the Map I choose.

I'm using Chunky 1.4.5 and java version 1.8.0_181 64 Bit on a debian 9.5
Regarding the HW: I'm running a Xeon w-2145 with 256 GB ram.
If you need any more Information please let me know.

Thanks for your help.

kind regards
Max