Need the Trainer.train accepts generator as training set

[lchild358]

Hello

I'm using generator to generate the training set, but it seems that at present, the method Trainer.train accepts only Array as training set. I think it can be improved for accepting generator as training set. I think it will be more convenient in case the training set is so large to be defined explicitly by Array.
(Of course, i can build the training set Array from generator, but it is not so efficient)

Thank you for your work!
Regard.