[#305] Add distance functions:

https://github.com/scalanlp/breeze/issues/305

- Euclidean distance
- Squared Euclidean distance
- Chebyshev distance
- Manhattan distance
- Minkowski distance
- Cosine distance
- Tanimoto distance

Because it is not easy for me to implement a weighted distance function in Breeze, I couldn't do.
I will try later, or could anyone please implement weighted distance functions.
in general you can use === and no assert message, and you'll get more or less the same message you wrote.