TODO: Fix Duplicator

When allowing IJ2's duplicator to override, it throws this when
duplicating the clown:

org.scijava.module.MethodCallException: Error executing method:
net.imagej.plugins.commands.imglib.DuplicateImage#initializer
	at org.scijava.module.MethodRef.execute(MethodRef.java:73)
	at
org.scijava.module.AbstractModule.initialize(AbstractModule.java:82)
	at
org.scijava.module.process.InitPreprocessor.process(InitPreprocessor.java:60)
	at
org.scijava.module.ModuleRunner.preProcess(ModuleRunner.java:104)
	at org.scijava.module.ModuleRunner.run(ModuleRunner.java:156)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:126)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:65)
	at
java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
	at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
	at java.lang.Thread.run(Thread.java:695)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.scijava.module.MethodRef.execute(MethodRef.java:69)
	... 11 more
Caused by: java.lang.NullPointerException
	at net.imglib2.meta.SpaceUtils.getAxisTypes(SpaceUtils.java:57)
	at
net.imagej.plugins.commands.imglib.DuplicateImage.initializer(DuplicateImage.java:196)
	... 16 more
An ImageDisplay is required but none exists

... when calling IJ2's 'Add' on two clowns
wip