style: fix compiler warnings

src/main/java/org/dts/spell/dictionary/OpenOfficeSpellDictionary.java

@@ -31,8 +31,7 @@ public class OpenOfficeSpellDictionary implements SpellDictionary
 {
   private File personalDict ;
   private MySpell mySpell ;
-  private boolean isLoaded = false ;
-  private Future loader = null ;
+  private Future<Object> loader = null ;
 
   //Emilio Gustavo Ormeño
   public OpenOfficeSpellDictionary(InputStream affIS, InputStream dicIS) throws IOException

src/main/java/org/dts/spell/dictionary/SpellDictionaryException.java

@@ -8,6 +8,7 @@
  * @author DreamTangerine
  *
  */
+@SuppressWarnings("serial")
 public class SpellDictionaryException extends Exception
 {
 

src/main/java/org/dts/spell/event/SpellCheckEvent.java

@@ -13,6 +13,7 @@
  * 
  * @author DreamTangerine ([email protected])
  */
+@SuppressWarnings("serial")
 public class SpellCheckEvent extends EventObject
 {
   private WordFinder finder ;  

src/main/java/org/dts/spell/finder/WordNotFoundException.java

@@ -1,5 +1,6 @@
 package org.dts.spell.finder;
 
+@SuppressWarnings("serial")
 public class WordNotFoundException extends RuntimeException {
 
   /**