Add new joystick features

Axis counts other than six and POVs are both present in C++ and Java now

Add dynamic joystick axis counts, up to 12

Change-Id: Ieade5e61a89df822df8702cb32326e4635558778

Add support for POVs in C++

Change-Id: I12dc0fcaca605a256ddcf990eebde45767229171

Make POVs work in Java

Change-Id: Ie2d98adb416c1930f058bdd21c3e7d26289df503

wpilibj/wpilibJavaSim/src/main/java/edu/wpi/first/wpilibj/Joystick.java

@@ -276,6 +276,15 @@ public class Joystick extends GenericHID {
         return m_ds.getStickButton(m_port, button);
     }
 
+    /**
+     * Get the state of a POV on the joystick.
+     *
+     * @return the angle of the POV in degrees, or -1 if the POV is not pressed.
+     */
+    public int getPOV(int pov) {
+        return 0; // TODO
+    }
+
     /**
      * Get buttons based on an enumerated type.
      *