Hello again.
Sorry for a long delay, but it took me some time to update the document
and the reference implementation. But finally, there is an update.
1. extract_heap_top() renamed to displace_top()
2. Added remove_heap function
3. Changed pop_heap wording (remove_heap() + pop_back())
4. Added benchmark results for `pop_heap() + pop_back()` against
`remove_heap() + pop_back()`. I wished to recheck my claim about
potential performance improvements.
5. Added motivation for adding freestanding functions
6. Different minor improvements.

Thank you in advance.

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Best regards,
Aleksei Sidorin.