Factored data labeling classes from viewer/__init__.py into labeleddata.py.
Added docs to stubs.
Added LabeledColumn class
Added DataTable class.
Added html pretty printing
Added html pretty printing
Code formatting in vsm/viewer/__init__.py
Merge branch 'labeleddata' of https://github.com/inpho/vsm into labeleddata
Merge branch 'labeleddata' into develop