Version R6 of P2300

add R0 of P2532, removing execution_ptr from receiver concepts

R4 (2022-02-15 mailing, 2022-01 Library Evolution polls)

R3 (2021-12-15 mailing, 2021-12-06/07 Library Evolution supertelecon).

R2 (2021-10-15 mailing).

R1 (2021-07-15 mailing).

R0 (2021-06-15 mailing).