The old definitions had some problems:
- In `lowerBound`, the `lhs` (left hand side) argument was passed on the
right hand side.
- In `upperBound`, the `greaterThan` function needed to return
`greaterThanOrEqual` for the function work, so either the name or the
implementation is incorrect.
To fix both problems, define the functions in terms of a `lessThan` function that returns `lhs < rhs`.
The is more consistent with the rest of `sort.zig` and it's also how C++ implements lower/upperBound (1)(2).
(1) https://en.cppreference.com/w/cpp/algorithm/lower_bound
(2) https://en.cppreference.com/w/cpp/algorithm/upper_bound
- Rewrite doc comments.
- Add a couple of more test cases.
- Add docstring for std.sort.binarySearch
e487b576fa