Remove the black "sphere" circle from Rotate manipulator

The black circle represented the ability to perform a trackball-like
arbitrary rotation in screen space. This functionality still exists, but
the black circle itself had no real purpose since you perform the
trackball rotation by clicking on empty space, not on any particular
circle.

The _circleSphere renderable is still present since it is used for mouse
selection, but it no longer renders on screen.

radiantcore/selection/BasicSelectable.h

@@ -10,31 +10,32 @@ namespace selection
  * Behaves just as one would expect, keeping track of
  * the selected state by means of a boolean.
  */
-class BasicSelectable : 
-	public ISelectable
+class BasicSelectable: public ISelectable
 {
-private:
-	bool _selected;
+    bool _selected = false;
 
 public:
-	BasicSelectable() :
-		_selected(false)
-	{}
-
-	void setSelected(bool select = true)
-	{
-		_selected = select;
-	}
-
-	bool isSelected() const
-	{
-		return _selected;
-	}
-
-	void invertSelected()
-	{
-		_selected = !_selected;
-	}
+
+    void setSelected(bool select = true) override
+    {
+        _selected = select;
+    }
+
+    bool isSelected() const override
+    {
+        return _selected;
+    }
+
+    void invertSelected()
+    {
+        _selected = !_selected;
+    }
 };
 
+/// Convenience function to call setSelected() on a number of items
+template<typename... Item> void setSelected(bool select, Item&&... item)
+{
+    (item.setSelected(select), ...);
+}
+
 } // namespace

radiantcore/selection/manipulators/RotateManipulator.cpp

@@ -52,7 +52,6 @@ void RotateManipulator::updateColours()
 	_circleY.setColour(colourSelected(COLOUR_Y(), _selectableY.isSelected()));
 	_circleZ.setColour(colourSelected(COLOUR_Z(), _selectableZ.isSelected()));
     _circleScreen.setColour(colourSelected(COLOUR_SCREEN(), _selectableScreen.isSelected()));
-    _circleSphere.setColour(colourSelected(COLOUR_SPHERE(), false));
 	_pivotPoint.setColour(colourSelected(COLOUR_SPHERE(), _selectablePivotPoint.isSelected()));
 }
 
@@ -139,7 +138,6 @@ void RotateManipulator::onPreRender(const RenderSystemPtr& renderSystem, const V
     _circleY.update(_lineShader);
     _circleZ.update(_lineShader);
     _circleScreen.update(_lineShader);
-    _circleSphere.update(_lineShader);
     _pivotPoint.update(_pivotPointShader);
     _angleText.update(_textRenderer);
 }
@@ -150,7 +148,6 @@ void RotateManipulator::clearRenderables()
     _circleY.clear();
     _circleZ.clear();
     _circleScreen.clear();
-    _circleSphere.clear();
     _pivotPoint.clear();
     _angleText.clear();
 
@@ -281,16 +278,12 @@ RotateManipulator::Component* RotateManipulator::getActiveComponent()
 
 void RotateManipulator::setSelected(bool select)
 {
-    _selectableX.setSelected(select);
-    _selectableY.setSelected(select);
-    _selectableZ.setSelected(select);
-    _selectableScreen.setSelected(select);
-	_selectablePivotPoint.setSelected(select);
+    selection::setSelected(select, _selectableX, _selectableY, _selectableZ,
+                           _selectableScreen, _selectablePivotPoint);
 
-	if (!select)
-	{
-		_rotateAxis.resetCurAngle();
-	}
+    if (!select) {
+        _rotateAxis.resetCurAngle();
+    }
 }
 
 bool RotateManipulator::isSelected() const