Add support for enums as multiple choice items

Thanks to Christian Dietz for reminding me.

Author: ctrueden

src/main/java/org/scijava/command/CommandModuleItem.java

@@ -155,11 +155,14 @@ public int getColumnCount() {
 
 	@Override
 	public List<T> getChoices() {
-		final ArrayList<T> choices = new ArrayList<T>();
+		final String[] choices = getParameter().choices();
+		if (choices.length == 0) return super.getChoices();
+
+		final ArrayList<T> choiceList = new ArrayList<T>();
 		for (final String choice : getParameter().choices()) {
-			choices.add(tValue(choice));
+			choiceList.add(tValue(choice));
 		}
-		return choices;
+		return choiceList;
 	}
 
 	// -- BasicDetails methods --

src/main/java/org/scijava/module/AbstractModuleItem.java

@@ -32,6 +32,7 @@
 package org.scijava.module;
 
 import java.lang.reflect.Type;
+import java.util.Arrays;
 import java.util.List;
 
 import org.scijava.AbstractBasicDetails;
@@ -258,7 +259,8 @@ public int getColumnCount() {
 
 	@Override
 	public List<T> getChoices() {
-		return null;
+		final T[] choices = getType().getEnumConstants();
+		return choices == null ? null : Arrays.asList(choices);
 	}
 
 	@Override