Fixes NPE on WB_Sphere with default constructor

The WB_Sphere class' default constructor will throw a NPE and so will classes that rely on WB_Sphere's default constructor. This is caused by sending an uninitialized WB_Point to the geometryfactory, causin' all kinds of trouble. The solution is to *not send it* and thus receive a new and initialized WB_Point in return. The code below displays the problem. The code has been tested after the patch and the problem is solved.

**Code Example**
```java
import wblut.math.*;
import wblut.processing.*;
import wblut.hemesh.*;
import wblut.geom.*;

// The WB_Sphere class' default constructor will throw a NPE
WB_Sphere sphere = new WB_Sphere();

// And so will classes that rely on WB_Sphere's default constructor
HEM_Spherify modifier = new HEM_Spherify();
```