Mali’s former prime minister Soumeylou Boubeye Maiga, arrested over corruption allegations last year, died of an undisclosed illness in hospital.   He died on Monday, March 21, one of his lawyers said.   Maiga, 68, was detained in August over his suspected role in the purchase of a presidential plane during the rule of ex-president Ibrahim Boubacar Keita, ousted in a military coup a year earlier.   He was charged with multiple counts of graft and was awaiting trial.   …