HRABOVE, Ukraine — Bowing to international pressure Monday, pro-Moscow separatists released a train packed with bodies and handed over the black boxes from the downed Malaysia Airlines plane, four days after it plunged into rebel-held eastern Ukraine. With body parts decaying in sweltering heat and signs that evidence at the crash site was mishandled, anger in Western capitals has mounted at the rebels and their allies in Moscow. Their reluctant cooperation will soothe mourning families and help investigators, but may do little to reconcile the East-West powers struggling over Ukraine's future.