Basic Control Scaling Implemented along the Top Tool Bar

In Widgets a class called ControlScale has been created. Into this can be
loaded a scene, a QSlider, and then a list of objects. The ControlScale is
passed to the rigGraphicsView, so when objects are selected then they can
be filtered out and scaling can occur on the appropriate controls in the
scene.

At the moment this is mostly implemented, with scaling on individual
objects working. However, scaling on muliple selections and scaling on
all controls of the same type has not been implemented.

Scaling needs to be passed down to the pins, so ControlPins are scaled
appropriately as well.

There is a checkbox on the toolbar called "Scale Matching Items". This has
not been implemented, but when it is then it will allow the user to scale
all controls in the scene to the same scale. So for example you could
shrink all of the guidemarkers...
Implementation of all scaling to single and multiple controls

Nearly all issues tidied up with regards scaling.

The ControlScale() checks that we have only one type of control selected.

The RigGView MouseReleaseEvent handles the mouse button release, and then
processes the controlList in case scale using the slider is about to take
place.

Scale now works on a selection or single Item. If the checkbox "Scale
Matching Items" is checked then the scale will apply to all scene Items of
the same type as the first item selected. This is used for more global
changes.

Fixed one tiny bug with the store method of supernodes, where an
additional arguement had to be passed to the pin.store()

Scaling still needs to be passed on to ControlPins

There is now bug with using Constraint Items, which conflicts with the new
scaling methods. This needs resolving.
Scaling cleaned up by filtering Items correctly

Checks are now in place for to check the first item in the control list in
mouseReleaseEvent (RigGraphicsView). If the first Item is of the wrong
type then the controllist is marked as not valid.

A bug has also been fixed with the loading (read) of superNode groups
losing the links to their constraintItems. This now loads properly.
Merge branch 'ControlScaleBranch'