added yet another python version

Different in these ways:
1) It only supports binary, not scalar. ( I am planning on adding scalar eventually.)
2) It doesn't use vectors for graphics card oprimization, so it is much slower.
3) It requires installing the cdecimal python library (but not R or numpy)
4) It is deterministic, so Macs and Windows and Linux all get identical outcomes. We avoid floating point operations.

The 4th property is the most important one. That is why this library can be used in a blockchain, but Paul's and Jack's cannot.