5b4e81b379 Implement Arbitrary for Transaction (Shing Him Ng)
Pull request description:
Implement `Arbitrary` for Transaction and its child types
ACKs for top commit:
apoelstra:
ACK 5b4e81b379 successfully ran local tests
tcharding:
ACK 5b4e81b379
Tree-SHA512: 411b97344e01e2bf38fff994902acda51f9a4fe748573e600fbdd643951a0a56b37395594349706b13c744304bd5396fd8ee31c27e5b1ff97e1a3cebd479e7c8