Remove winapi support in favor of examples

[KodrAus]

Closes #537

Instead of worrying about a conversion library right now this just removes the winapi support and adds some examples of creating UUIDs from GUIDs. We can't be certain that all GUIDs can be converted into UUIDs without flipping fields so our to_guid and from_guid methods don't seem like they could ever be guaranteed to always be correct.

[KodrAus]

I've also fixed up my broken changes to the v1::Context so it goes back to its old implementation of always incrementing the counter, but will wrap on the max value representable by the UUID, not the max value in a usize.