Partial Expression implemented with Selections

The system now records your selection before moving an ExpressionStateNode
slider, and then the slider will only act on the nodes that were selected.
Using the mousePress/ReleaseEvents in the slider the selection of the
rigGV is then restored afterwards.

The expression monitoring includes each ExpressionItemState having a
"selected" attribute. If no nodes are selected then the entire expression
is dialled in across all nodes.

The selection state for each node is collected for the whole view in the
mapSelected method of the ExpressionCaptureProcessor.
ExpressionStateNode now collects colour data from ExpressionFaceState

Attempting to collect all major data in the ExpressionFaceState. This way
only this needs to be saved and loaded, and it can create the appropriate
graphical representation when it does so (creating a new
ExpressionStateNode on read).

Appropirate attributes added to the ExpressonFaceState so that it can
record colour and position information for both the ExpressionStateNode
and its slider.
ClearAll method added to ExpressionCaptureProcessor

This method is added to clear out all expression library and faceSnapShot
data in the event of the whole rigGV being cleared.
ExpressionCapture Processor store/read blocked in

The methods read and store have been blocked in without syntax error all
the way down the expression system levels. Very limited testing. RigStore
is updated to try and record the ExpressionSystem in XML.

Initial Problem is that the faceSnapShot is a ExpressionFaceState, but has
no ExpressionStateNode associated with it, so things like getPos() fail
when store() is called. Look at changing store and read behaviour
depending on the existence of an ExpressionStateNode...
Expression System Saves and Loads, but is flawed on Load.

Expression system slider stuff etc is over engineered and built by hand in
a messy way. It turns out that you can use QGraphicsWidget to actually
build widgets directly into the graphics view. Fortunately functionality
is split off, so now I am going to be rewriting the ExpressionStateNode as
a QGraphicsWidget instead, with a QGraphicsLayout with a label and a
slider. This is last stand of the old system...
New ExpressionStateNode implemented in ControlItems

This is the rewrite of the old ExpressionStateNode with its
ExpressionPercentageSlider. The new class subclasses QGraphicsWidget,
which allows you to embed other QWidgets in the QGraphics View. As such
the QGraphicsWidget takes a QLabel and QSlider as inputs and builds a
small box around them with a nice colour background.

Functionality has not had to be adjusted, and at this stage there are
still old methods left in the ExpressionCapture systems mainly
ExpressionFaceStates that are now redundant.

Read and Store is not implemented. This needs to be cleaned up now...