Generate C Code for Multiple Types

The next immediate step is to:

1. Generate C code for multiple ASN.1 type definitions in a module.
2. Add some unit tests for generating C code so that any future modifications that affect C code generation are caught before a patch is committed.

Probably the steps after that are to:

1. Automate (script) testing against asn1c.
2. Add unit tests for e.g. enumerated types and component of types.
3. Beef up QuickCheck testing.