Picklists of literals

Constraint values of constraint type LitPicklist are interpreted as lists.

shapeID	propertyID	value_type	constraint_value	constraint_type
:book	:color		red green yellow	LitPicklist
:book	:color		red	LitPicklist

This is interpreted as:

DCAP
    Shape
        shapeID: :book
        start: True
        Statement
            propertyID: :color
            constraint_value: ['red', 'green', 'yellow']
            constraint_type: LitPicklist
        Statement
            propertyID: :color
            constraint_value: ['red']
            constraint_type: LitPicklist