Reordered and renamed several methods
Experimenting with goc for vector operations.
Go implementation:

BenchmarkDist2    100000             18380 ns/op
BenchmarkLeastSquare     2000000               840 ns/op

C implementation:

BenchmarkDist2    200000             10788 ns/op
BenchmarkLeastSquare     2000000               968 ns/op
Profiling digits sample
Added old implementation for easier comparison if needed.