Fix potential lock when opening a new game while a resource contains …

…unsaved data

src/org/infinity/resource/key/AbstractBIFFReader.java

@@ -43,7 +43,7 @@ public enum Type {
    * @return A BIFFReader object for accessing the BIFF archive.
    * @throws IOException On error.
    */
-  public static synchronized AbstractBIFFReader open(Path file) throws Exception {
+  public static AbstractBIFFReader open(Path file) throws Exception {
     return queryBIFFReader(file);
   }