We will need to implement many metrics, so we should split it into a package.
Add metric interface, add polynomial kernel.
Remove Metric interface, add RBFKernel.
Temp change some code so we can build via goconvey.
Add basic test to euclidean.
Add euclidean distance test.
Use gonum/matrix/mat64, life is easier.
We don't need to manually handle error anymore.
Migrate to mat64 in poly_kernel.
Remove examples, remove CheckDimMatch.
Add basic PolyKernel and RBFKernel test.
Add manhattan distance.
Make manhattan support both col&row vectors.
Add documents.
Add doc link to README.
Merge pull request #12 from sjwhitworth/metrics

Metrics