Parses the specification for an inductive type into a structured format.
DESCRIPTION
The underlying function define_type_raw used inside define_type expects the
inductive type specification in a more structured format. The function
parse_inductive_type_specification parses the usual string form as handed to
define_type and yields this structured form. In fact, define_type is just
the composition of define_type_raw and parse_inductive_type_specification.
FAILURE CONDITIONS
Fails if there is a parsing error in the inductive type specification.