dec05b63e9 Refactor witness_version and is_witness_program (Tobin C. Harding)
dac552b436 Add unit tests for shortest/longest witness program (Tobin C. Harding)
Pull request description:
Refactor `witness_version` and `is_witness_program`.
- Patch 2 adds a couple of preparatory unit tests.
- Patch 2 does the refactor
Fix: #2618
ACKs for top commit:
apoelstra:
ACK dec05b63e9
sanket1729:
ACK dec05b63e9
Tree-SHA512: 3db0a1d8175cbb2fd18f3254854d02db3ad7efa2620b12f08d9727ef6bb5854f0a015917e57023cd2196a36d13276e80536a0e96318c44a1173da4f6793ca370