Make FP16 / FP32 choosable by user

Some cards (GCN 4.0) are the same speed with FP16 and FP32 models. But since the FP16 models require less VRAM, in some cases it would be beneficial to force the FP16 variant manually.

I have seen some examples in the past where the FP32 Model was chosen, maybe this is obsolete, haven´t checked, but in case its stillt there - my request it is :slight_smile: