Prepare trap of hardware/mem failures
faster x15, +23KH or 4ms on whirpool (30ms vs 34ms)

tpruvot: i didnt pick the asm replace_hiword, slower on linux
stratum: handle optional mining.set_extranonce

allow pools to switch more coins without reconnect

Tested ok on a nicehash x11 pool

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>