deprecate legacy files

src/main/java/de/marhali/easyi18n/util/IOUtil.java

@@ -15,6 +15,7 @@ import java.io.File;
  * IO operations utility.
  * @author marhali
  */
+@Deprecated
 public class IOUtil {
 
     /**

src/main/java/de/marhali/easyi18n/util/array/ArrayUtil.java

@@ -13,6 +13,7 @@ import java.util.regex.Pattern;
  * Utility methods for simple array support.
  * @author marhali
  */
+@Deprecated
 public abstract class ArrayUtil {
 
     static final String PREFIX = "!arr[";

src/main/java/de/marhali/easyi18n/util/array/JsonArrayUtil.java

@@ -7,6 +7,7 @@ import com.google.gson.JsonElement;
  * Utility methods to read and write json arrays.
  * @author marhali
  */
+@Deprecated
 public class JsonArrayUtil extends ArrayUtil {
     public static String read(JsonArray array) {
         return read(array.iterator(), JsonElement::getAsString);