fix indexing for sampling (float32 indices are deprecated)
fix indexing for sampling (float32 indices are deprecated)

yang1fan2/nematus,rsennrich/nematus,yang1fan2/nematus,rsennrich/nematus,EdinburghNLP/nematus,EdinburghNLP/nematus,Proyag/nematus,cshanbo/nematus,rsennrich/nematus,rsennrich/nematus,yang1fan2/nematus,yang1fan2/nematus,rsennrich/nematus,yang1fan2/nematus,EdinburghNLP/nematus,Proyag/nematus,Proyag/nematus,shuoyangd/nematus,shuoyangd/nematus,cshanbo/nematus,cshanbo/nematus,cshanbo/nematus,yang1fan2/nematus,shuoyangd/nematus,yang1fan2/nematus,EdinburghNLP/nematus,cshanbo/nematus,yang1fan2/nematus,Proyag/nematus,Proyag/nematus,yang1fan2/nematus,Proyag/nematus,yang1fan2/nematus,shuoyangd/nematus,EdinburghNLP/nematus,EdinburghNLP/nematus,shuoyangd/nematus,cshanbo/nematus,shuoyangd/nematus,rsennrich/nematus