New change interface and changeManager class

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+
+import java.util.*;
+
+/**

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+import java.util.*;
+
+/**
+ * @param <C> the change types to store in this change manager

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+	private int	markedIndex;
+
+	/**
+	 * Adds a change to the changes list.

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+	}
+
+	/**
+	 * Undoes the change at the current index position.

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+	/**
+	 * Undoes the change at the current index position.
+	 * 
+	 * @return whether the operation could be executed due to one being currently available

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+	/**
+	 * Applies the change that was undone before.
+	 * 
+	 * @return whether the operation could be executed due to one being currently available

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+	}
+
+	/**
+	 * Marks the current index.

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+	}
+
+	/**
+	 * @return whether the current index was marked

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+	}
+
+	/**
+	 * @return whether the undo operation is currently available

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+	}
+
+	/**
+	 * @return whether the redo operation is currently available.

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+ * @author Maximilian Käfer
+ * @since 0.0.1
+ */
+public final class ChangeManager<C extends Change> {

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+	 */
+	public boolean undo() {
+		if (isUndoAvailable()) {
+			changes.get(index).invert().apply();

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+		if (isUndoAvailable()) {
+			changes.get(index).invert().apply();
+			--index;
+			return true;

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+		if (isRedoAvailable()) {
+			changes.get(index + 1).apply();
+			++index;
+			return true;