The commit ab5ae32bae is the last commit
for the second edition, so all changes since then are dropped except for
several commits for the third edition authored by Andreas Antonopoulos.
No attempt is made to remove CC-BY-SA or other licensed content present
in the already-published first or second editions.
This revert may itself be reverted for versions of the book published
under CC-BY-SA.
The bug is that `x % 255` is not quite the same thing as `x % 256`;
but `x & 255` is.
The stylistic issue is that `numeric_limits<uint8_t>::max()` is a
very verbose way of spelling `255`.
