Add Float16

[pyrtsa (Pyry Jahkola)]

@Karl

In that case, I'd just assumed that, since S4TF is bringing lots of developers familiar with Python, they might have chosen Float meaning a float from Python (when they meant a Swift Double ).

I don't think that's a concern. In fact, while Python's float is 64-bit, the numeric Python community is quite used to choosing between float16, float32, and float64. Those names are used by NumPy and indeed TensorFlow.