parse_type extends the parse module (opposite of string.format()) with the
following features:
* build type converters for common use cases (enum/mapping, choice)
* build a type converter with a cardinality constraint (0..1, 0..*, 1..*) from
the type converter with cardinality=1.
* compose a type converter from other type converters
* an extended parser that supports the CardinalityField naming schema and
creates missing type variants (0..1, 0..*, 1..*) from the primary type
converter
