NonInvertibleTransformException improvements.

We only need one copy of this class, and it dang well better not be a checked
exception.

src/main/java/pythagoras/d/AffineTransform.java

@@ -6,6 +6,7 @@ package pythagoras.d;
 
 import java.io.Serializable;
 
+import pythagoras.util.NoninvertibleTransformException;
 import pythagoras.util.Platform;
 
 /**

src/main/java/pythagoras/f/AffineTransform.java

@@ -6,6 +6,7 @@ package pythagoras.f;
 
 import java.io.Serializable;
 
+import pythagoras.util.NoninvertibleTransformException;
 import pythagoras.util.Platform;
 
 /**

src/main/java/pythagoras/f/NoninvertibleTransformException.java

@@ -1,16 +0,0 @@
-//
-// Pythagoras - a collection of geometry classes
-// http://github.com/samskivert/pythagoras
-
-package pythagoras.f;
-
-/**
- * An exception thrown by {@link AffineTransform} when a request for an inverse transform cannot be
- * satisfied.
- */
-public class NoninvertibleTransformException extends java.lang.Exception
-{
-    public NoninvertibleTransformException (String s) {
-        super(s);
-    }
-}

src/main/java/pythagoras/util/NoninvertibleTransformException.java

@@ -2,13 +2,13 @@
 // Pythagoras - a collection of geometry classes
 // http://github.com/samskivert/pythagoras
 
-package pythagoras.d;
+package pythagoras.util;
 
 /**
- * An exception thrown by {@link AffineTransform} when a request for an inverse transform cannot be
+ * An exception thrown by {@code AffineTransform} when a request for an inverse transform cannot be
  * satisfied.
  */
-public class NoninvertibleTransformException extends java.lang.Exception
+public class NoninvertibleTransformException extends java.lang.RuntimeException
 {
     public NoninvertibleTransformException (String s) {
         super(s);