[CHANGES]
- Have pairs() return blessed objects that recognise ->key and
->value as well as being two-element ARRAYs
- Booleanise the result of looks_like_number() so as not to
accidentally leak abstraction (RT94806)
- Document the version each function was added in (RT96220)
[BUGFIXES]
- Try to preserve UV precision in sum() where possible (RT95902)
- Document known lexical capture in pairmap bug RT95409
- SvGETMAGIC() in set_prototype() (RT72080)