bae264d0c2 Add `tapscript_leaf_hash()` to `Script` (Jiri Jakes)
Pull request description:
Adds convenience method to `Script` for computing leaf hash of tapscript. Closes#1482.
The little test case is taken from `bip341_tests.json`.
ACKs for top commit:
Kixunil:
ACK bae264d0c2
apoelstra:
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Tree-SHA512: fb7a3a552017208decd56ca7d27eab1987a3a92aae5b8620896b3a02986c2fc13043c200ccfbadf9cfdd2d74af38b0bc25936338f55b7d318c1296acc88bf22a