1e0e712bb0 Add push_* methods for lock times (Tobin C. Harding)
Pull request description:
Lock times are `u32` and can require encoding using 5 bytes.
Add methods `push_lock_time` and `push_sequence` for pushing absolute lock times and sequence numbers. We do not push relative locktimes because they are only 16 bits from the original sequence number.
ACKs for top commit:
Kixunil:
ACK 1e0e712bb0
apoelstra:
ACK 1e0e712bb0
Tree-SHA512: 4b511679270e7ef73937259ccf7d1b9b4b7512b2464f302310519a6e02d55c9cc24e3559302aeb671156e68130478258c1c565f474880e8be708b0ee234e67ff