Renamed spec_type to object_type for Specifications
Updated LabelDecorator constructor with name and type_required arguments
The setup_sheets method no longer needs to return SheetSpec objects

The properties of all the sheets at a given level are now specified
either using a Python literal or a Lancet Args object. The type of the
sheet is obtained from the argument supplied to the level decorator.
Updated Lancet submodule reference
Updated decorated method names as suggested by Jim
Updated incorrect docstring
Add analysis notebook
Don't show individual lags, remove register=False