This is not a generic UNIX timestamp, but rather a MTP restricted to
have values between 500 million and u32::MAX. Most importantly, it is
*not* a blocktime, which is what is implied by its name and
constructors.
Add an integration test the verifies we have serde traits implemented
for all the main crate types (excl. errors and helper structs).
This also acts as a regression test.
Fmt Bot
Tobin C. Harding
Andrew Poelstra