Fix #1289 Matrix3f/Matrix4f equals() should require an exact class match (#1302)

jme3-core/src/main/java/com/jme3/math/Matrix3f.java

@@ -1210,7 +1210,7 @@ public final class Matrix3f implements Savable, Cloneable, java.io.Serializable
      */
     @Override
     public boolean equals(Object o) {
-        if (!(o instanceof Matrix3f)) {
+        if (o == null || o.getClass() != getClass()) {
             return false;
         }
 

jme3-core/src/main/java/com/jme3/math/Matrix4f.java

@@ -2161,7 +2161,7 @@ public final class Matrix4f implements Savable, Cloneable, java.io.Serializable
      */
     @Override
     public boolean equals(Object o) {
-        if (!(o instanceof Matrix4f)) {
+        if (o == null || o.getClass() != getClass()) {
             return false;
         }