Implemented basic SuperNode Storing

SuperNode store works for basic attributes and saves to XML. Need to test
the saving of SkinningInfo and the loading of both SuperNodes and
SkinningInfo.
Saving and Reading of SuperNodes and Skinning Complete

This is a milestone from the point of view in practice all saving and
loading of the functonality is now possible. This means that complex faces
can now be stored and reloaded.

Restrictions are that nodes can currently only be skinned properly to one
superNode. Yuo can skin to more, but the values will fight overriding
eachother in a way that is very confusing. Consider adding multiple
superNode influences to SkinningInfo. Discussion on how to do this.

In this commit there are also a number of doc strings added to try and
make it clearer the purpose of each class. doc strings for classes will be
the priority, followed by doc strings for complex or unintuitive methods.
DocStrings updated for all Items in ControlItems.py
Additional Docstrings added for classes in other files

DocStrings added to describe the main purpose and interaction of all
classes in the FaceBase_Launch.py, FileControl.py, RigStore.py
Utilities.py adn Widgets.py. Some more details still need to be added to
the main subclassed RigGraphicsView.

Once all of this is done then a second wave of Docstrings will be
implemented for the major functions within each class. Currently only a
handful of functions are commented in any detail.
Merge branch 'updateDocString-branch'
Use message logger in file IO code
Correct indentation error
Abbreviate RigUIControls to rig

Simply to shorten lines and perhaps make it easier if we rename the
module to be more pep-8 conformant.
Switch to ItemFactory from eval() method

Eval should be considered dangerous so we switch to a cleaner table
lookup mechanism for figuring out what classes to create from the text
mime data from the drop event.

We add .name class level values to the widget classes and construct a
table of name -> constructor pairs. This keeps the look up name nice and
close to the class definition.

We also change to using the .name attributes instead of the strings when
creating the DragItem controls to make sure everything stays in sync.
Code cleanup

Just white space changes and comments and "Select Markers" -> "Select
Guide Markers".
Merge branch 'itemfactory'