Add support for distinct base types

[mratsim]

Some libraries define distinct types to avoid mixing types with a semantically different purpose, for example:

• type Miles = distinct float32 and type Meters = distinct float32 in a physics engine
• or type SecretBool = distinct uint64 in a cryptographic library

It would be useful to support distinct types:

• either by automatically replacing them by their base type when exporting a proc
• or creating a typedef