Made the JavaClass#Iterator a supplier, fixes multiple engine runs

JavaBytecodeCompiler/src/main/java/org/openzen/zenscript/javabytecode/compiler/JavaForeachWriter.java

 import org.openzen.zenscript.javashared.JavaMethod;
 import org.openzen.zenscript.javashared.JavaModifiers;
 
-import java.util.HashMap;
 import java.util.Map;
 @SuppressWarnings("Duplicates")
 public class JavaForeachWriter {
         
         javaWriter.label(startLabel);
         javaWriter.dup();
-        javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR, "hasNext", "()Z", 0));
+        javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR.get(), "hasNext", "()Z", 0));
         javaWriter.ifEQ(endLabel);
         javaWriter.dup();
-        javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR, "next", "()Ljava/lang/Object;", 0));
+        javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR.get(), "next", "()Ljava/lang/Object;", 0));
         
         final JavaLocalVariableInfo keyVariable = javaWriter.getLocalVariable(variables[0].variable);
         this.downCast(0, keyVariable.type);
 
 		javaWriter.label(startLabel);
 		javaWriter.dup();
-		javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR, "hasNext", "()Z", 0));
+		javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR.get(), "hasNext", "()Z", 0));
 		javaWriter.ifEQ(endLabel);
 		javaWriter.dup();
-		javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR, "next", "()Ljava/lang/Object;", 0));
+		javaWriter.invokeInterface(JavaMethod.getVirtual(JavaClass.ITERATOR.get(), "next", "()Ljava/lang/Object;", 0));
 		javaWriter.checkCast(Type.getType(Map.Entry.class));
 		javaWriter.dup(false);
 

JavaShared/src/main/java/org/openzen/zenscript/javashared/JavaClass.java

  */
 package org.openzen.zenscript.javashared;
 
-import java.util.Arrays;
 import stdlib.Strings;
 
+import java.util.Arrays;
+import java.util.function.Supplier;
+
 /**
  *
  * @author Hoofdgebruiker
 	public static final JavaClass CLOSEABLE = new JavaClass("java.lang", "AutoCloseable", Kind.INTERFACE);
 	public static final JavaClass MAP = new JavaClass("java.util", "Map", JavaClass.Kind.INTERFACE);
 	public static final JavaClass HASHMAP = new JavaClass("java.util", "HashMap", JavaClass.Kind.CLASS);
-	public static final JavaClass ITERATOR = new JavaClass("java.util", "Iterator", JavaClass.Kind.INTERFACE);
+	public static final Supplier<JavaClass> ITERATOR = () -> new JavaClass("java.util", "Iterator", JavaClass.Kind.INTERFACE);
 	public static final JavaClass ARRAYS = new JavaClass("java.util", "Arrays", Kind.CLASS);
 	
 	public static final JavaClass BOOLEAN = new JavaClass("java.lang", "Boolean", Kind.CLASS);

JavaShared/src/main/java/org/openzen/zenscript/javashared/prepare/JavaPrepareDefinitionVisitor.java

 		}
 		
 		{
-			JavaNativeClass iterator = new JavaNativeClass(JavaClass.ITERATOR);
+			JavaNativeClass iterator = new JavaNativeClass(JavaClass.ITERATOR.get());
 			iterator.addMethod("empty", new JavaMethod(JavaClass.COLLECTIONS, JavaMethod.Kind.STATIC, "emptyIterator", false, "()Ljava/lang/Iterator;", JavaModifiers.STATIC | JavaModifiers.PUBLIC, false));
 			iterator.addInstanceMethod("hasNext", "hasNext", "()Z");
 			iterator.addInstanceMethod("next", "next", "()Ljava/lang/Object;");