Generation of 'external' declarations from types.
Add bigarray support for external declarations.
Generate wrapper functions for ml stubs.
Disable 'noalloc' for the moment.

We need an interface for specifying interaction with callbacks.
Disable the "float" attribute for the moment.
Give views and structured types an identity.
A registry for views and structured types.
Resolve views and structured types using the registry.
ML signature generation.
Prettier printing of generated ML: omit parentheses where possible.
Free structs and unions returned by value.
A module of types and functions used in generated bindings.
Stub generation tests.
Test for calling atomic builtins via stub generation.
Test calling type-generic macros via generated stubs.
Split `MakePtr into `MakePtr and `MakeStructured
Generate ML types for bigarray types.
Support for generating signatures for ML bindings.
Pretty printing for generated ML.
Parenthesize return types of external bindings.