MirageOS signatures for network stacks

mirage-stack provides a set of module types which libraries intended to be used as MirageOS network stacks should implement.

The set of protocols defined is:

[Mirage_stack.STACKV4](stackv4) and [Mirage_stack_lwt.STACKV4](stackv4-lwt)

mirage-stack is distributed under the ISC license.

[stackv4]: https://mirage.github.io/mirage-stack/Mirage_stack.html
[stackv4-lwt]: https://mirage.github.io/mirage-stack/Mirage_stack_lwt.html