P0429 A Standard flatmap

[jensmaurer]

P0429R6 A Standard flatmap (Zach Laine)

https://issues.isocpp.org/show_bug.cgi?id=118

[mclow]

Reviewed on Tuesday; Zach will return with an updated paper later in the week.

[jensmaurer]

LEWG in Kona

[jensmaurer]

LWG in Kona

[wg21bot]

P0429R7 A Standard flat_map (Zach Laine)

[mclow]

This was not adopted for C++20. Removing the "C++20" label.