By JAMES ROBSON
AP Soccer Writer
DOHA, Qatar (AP) — Roberto Martinez said his goodbyes and left with his next whereabouts unknown. It is the end of an era for Belgium’s golden generation. But for the man who led it to third place at the 2018 World Cup it is the beginning of something new. A return to club soccer is on Martinez’ horizon after his six years in charge of Belgium ended in elimination at the group stage in Qatar. Precisely which club may be dependent on how the Spanish coach’s time with Belgium’s most celebrated group of players is assessed.