Fixes #1905: Export bus now considers failed crafting requests

The export bus will now no longer speed up, if more than 1 of the last
crafting requests failed and slow down, if more then 5 failed.

Some code cleanup and moved the custom iterator into the helper package
as it is clearly related to the craftingtracker and not the export bus.

src/main/java/appeng/helpers/NonNullArrayIterator.java

@@ -0,0 +1,63 @@
+/*
+ * This file is part of Applied Energistics 2.
+ * Copyright (c) 2013 - 2014, AlgorithmX2, All rights reserved.
+ *
+ * Applied Energistics 2 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Applied Energistics 2 is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Applied Energistics 2.  If not, see <http://www.gnu.org/licenses/lgpl>.
+ */
+
+package appeng.helpers;
+
+
+import java.util.Iterator;
+
+import scala.NotImplementedError;
+
+
+public class NonNullArrayIterator<E> implements Iterator<E>
+{
+
+	private final E[] g;
+	private int offset = 0;
+
+	public NonNullArrayIterator( E[] o )
+	{
+		this.g = o;
+	}
+
+	@Override
+	public boolean hasNext()
+	{
+		while( this.offset < this.g.length && this.g[this.offset] == null )
+		{
+			this.offset++;
+		}
+
+		return this.offset != this.g.length;
+	}
+
+	@Override
+	public E next()
+	{
+		final E result = this.g[this.offset];
+		this.offset++;
+
+		return result;
+	}
+
+	@Override
+	public void remove()
+	{
+		throw new NotImplementedError();
+	}
+}