This renames `Script` to `ScriptBuf` and adds unsized `Script` modeled
after `PathBuf`/`Path`. The change cleans up the API a bit, especially
all functions that previously accepted `&Script` now accept truly
borrowed version. Some functions that perviously accepted `&[u8]` can
now accept `&Script` because constructing it is no loger costly.
This can be replicated by deleting the `type PackedLockTime = LockTime'
line, and then running
find . -type f | xargs sed -i 's/PackedLockTime/LockTime/g
at the root of the repo.
Martin Habovstiak
Andrew Poelstra
Tobin C. Harding
DanGould