use mvc for the testbed, update almost all tests, bugfixes, improvements, cleanup

Since I started altering the testbed for better maintainability, I prefered to drop this (tested) large change with a single commit. Some changes below:

Put some globals in their correct place,

Now Testbed uses the MVC pattern (Model-View Controller). This way it becomes better to maintain than using no pattern  in my opinion.

Fixed some bugs in the debug draw interface.

Of course, updated almost all tests because of the differences.

Update script.

include/bounce/dynamics/cloth/cloth.h

@@ -23,7 +23,6 @@
 #include <bounce/collision/collision.h>
 
 struct b3Mesh;
-class b3Draw;
 
 struct b3ClothDef
 {
@@ -110,7 +109,7 @@ public:
 		return m_ps;
 	}
 
-	void Draw(b3Draw* draw) const;
+	void Draw() const;
 private:
 	void SolveC1();
 	void SolveC2();

include/bounce/dynamics/cloth/spring_cloth.h

@@ -25,7 +25,6 @@
 #define B3_CLOTH_SHAPE_CAPACITY 32
 
 class b3StackAllocator;
-class b3Draw;
 
 class b3Shape;
 
@@ -188,7 +187,7 @@ public:
 	void Apply() const;
 
 	// Debug draw the cloth mesh.
-	void Draw(b3Draw* draw) const;
+	void Draw() const;
 protected:
 	friend class b3SpringSolver;